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QUOTE (Daklu @ May 15 2009, 08:45 PM) Theres also one in the examples directory It just confused me at first because I expected everything you have under exterfaces for the agilent to be in the same place as the Device drivers. And a "thin" wrapper under the exterfaces like the others. But looking closer, your ACE and BAM ect are really simulators???? QUOTE (Daklu @ May 15 2009, 08:45 PM) Yes, but that is typically just a matter of downloading and installing them. No coding required. Hmmm. Wasn't the case for the agilent. I think even if it was an active X component you would still have to write some wrappers. Be nice if it was like that though. Download and install just like a video driver in windows etc. QUOTE (Daklu @ May 15 2009, 08:45 PM) Yeah, if I had to derive 20 child classes containing essentially the same code every three months exterfaces would get old really quick--regardless of how thin and light they are. I'm really curious what kind of testing you're doing that contains so many instruments used for such a short time. It sounds like a fairly chaotic environment. I also think it would be interesting if you did a white paper and sample project. Share the knowledge so we're not all reinventing the same thing. I think I referred to the current one on the Q's thread. If your really interested I'll take some pictures of it on Monday and PM them to you. Generally they are production inspection/test machines that have all sorts of measurements for inspecting things like turbo bushes, gudgeon pins, train brake valves. So they can have bowl feeders, motors, measurement probes, micrometers, laser distance meters, cameras and all sorts. We might get an order for a couple at most, but they are custom built to spec for specific production lines of our customers. Don't mind sharing, but write a paper? I wouldn't know where to start QUOTE (Daklu @ May 15 2009, 08:45 PM) Question: As Shoneill pointed out, exterfaces and polyconfigurism are different solutions for slightly different problems. Is there a way to combine them and gain the advantages of both? Off the top of my head I think it would just unnecessarily complicate things, but maybe you can think of something. Well. this is why I'm still in the thread. I think it can be done. Although I'm still looking for the elegant angle and a way to slowly introduce it rather than throw everything out the window and start again since time constraints would make this impossible (if its not broke....don't fix it). The way I'm looking at it is this. At the "mid" layer we both arrive at the same point, where the functional abstraction is realised and the underlying interfacing mechanics is transparent (although via different means). I'm loath to switch to classes because I can see a lot of work in maintaining the abstraction from project to project which I currently don't have. But. The sorts of tests/inspections are pretty much constant (once you've measured one tubular piece of metals' diameter the method works for all tubular pieces of metal which is basically what a gudgeon pin or turbo bush is). Its only the hardware that changes (bigger/smaller/more motors, more/less accurate micrometers electrical instead of air etc). So my "Top" is fairly constant" but my "bottom" is fat fluid. Your "Top" is fluid, but your "bottom" is constant. But in the middle (where your exterfaces sit as I see it). We have the same goal. What I do have from project to project at present is a constantly changing "mid" layer where the glue between top and bottom could be a lot better and I haven't so far found an elegant solution for this. QUOTE (Daklu @ May 15 2009, 08:45 PM) LUT? Look Up Table. ------------------------------ P.S. If your going to use the word "Polyconfigurism" then i'm going to call your "exterfaces" "Midglue"

Well. You don't have much for us to go on. In your temp vi, you don't really need 2 loops but it a long, long way from being able to manage a greenhouse. Did you take a look at the example in the examples directory. I think your lecturer might be looking for something like that for a remote monitoring system. In your other VI its not really defined what you want to do? Is there a temperature and humidity control for each crop? Or will it tell the greengrocer how much the seeds are.

QUOTE (Daklu @ May 15 2009, 02:20 AM) Well. If it's a dll driver we won't use it as its not cross platform, so it wouldn't be considered at the Systems Design Stage. The NI one is interesting, I haven't come across that before and at a first glance I'd say it is in the 10% area. QUOTE (Daklu @ May 15 2009, 02:20 AM) I also still don't understand how you have one read function work for different instruments. Suppose (for example) you're measuring peak-to-peak voltages on an oscilloscope. What if one scope returns the value in volts and another returns the value as the number of divisions and requires you to calculate the voltage? Haven't come accross one of those in a long time. The table I was describing can have a formatting string for the read and write. But I havn't had to use that feature in along while and I'm not even sure I can remember the syntax off hand QUOTE (Daklu @ May 15 2009, 02:20 AM) Sort of. Your interface definition defines the higher level functions. The exterface implements the higher level functions for each instrument that you want to use for those higher level functions. So you do have to wrap more than one piece of code... unless all your instruments use string based commands, then you can probably use polyconfigurism and a single vi. Woohooo. Thats what I was thinking. QUOTE (Daklu @ May 15 2009, 02:20 AM) I'm not sure we're on the same page here yet. The 34401 code I added is an exterface, not a device driver. You would still need the 34401 device driver from agilent to get the exterface to work. That IS the device driver from Agilent. You don't need anything else. QUOTE (Daklu @ May 15 2009, 02:20 AM) Except since my interface definitions are on the project level, it's no big deal to add "Personal Servant.vi" to what I already have. I don't have to worry about coding for exceptions that may occur in future applications or maintaining compatibility with previously deployed applications that use the interface. I just have to worry about making it work in this application. And adding the drivers I think I get the picture. You have a small set of instruments that don't change much (might be adding one every six months maybe). Whereas once you have your 3 instruments, you are pretty much done with the drivers and everything else is just using them or building on what you have already I have the difficulty that I may have 20 instruments on that project and will never see those instruments again, and there will be another 20 different ones in 3 months time on the next project. Like I think you pointed out. Its the difference between engineering tools and product.

QUOTE (shoneill @ May 15 2009, 08:20 AM) Not quite. We use DIO and AIO, but they sit on the RS485 or TCPIP bus. I suppose its the difference between being able to spec the instruments and just being handed them and have to deal with it. But they will be from different manufactures and have different command sets from project to project. And were not just talking 1 or 2 instruments per project here. Were talking between 10 and 30. QUOTE (shoneill @ May 15 2009, 08:20 AM) Exactly. One implementation is INDEPENDENT of the protocols used with the instrument(s) whereas the other is not. Ummmm . as far as I can tell they are both independent. There still has to be a way of explaining to the instruments what you want them to do in their own language regardless if it is a class or not. In OOP you create a class based around the common functions in the drivers, and that class (the Agilent, ACE or BAM Class for example) has the specifics for that instrument with a unified set of properties and methods (Configure, Read, Write set this, set that for example). You may have "inherited" and overridden a base class of "instrument", but the commands sets still have to be implemented for every instrument and function that you support. It's not until you abstract the function (like Configure) that every "Driver" has in its methods list that you get the independence. The file example does it a little bit differently but the upper layers of the software are the same as your describing. It doesn't care what the instrument is, or what functions the instrument supports. It's a scripting utility that (almost) blindly reads the file and squirts out the contents over an interface. And that interface can be any hardware platform you choose to support. The file defines what is and isn't sent , what the protocol/command set is and (as you've probably seen by the filenames) the target device(s). At the upper levels of the software, you have your configure, read and write as you would in classes, but you don't have to worry about creating the Agilent, BAM and ACE classes and exposing all the properties and methods. Just a file. This means if I replace the BAM, ACE or Agilient with a Keithly,, I just add a file to configure it and no software changes. Choosing which file, switches from one to another (on the fly if necessary). But his isn't about my "old" file thingy. this is about exterfaces. The merit I see in Daklus implementation (which I think we agree on) is not at the driver level, its at the function level where we both sit, files and classes alike. QUOTE (shoneill @ May 15 2009, 08:20 AM) With LVOOP ALL protocol-specific information and code is encapsulated within the class. With LVOOP I can release plug-in modules which will work seamlessly with the parent VI without having to change a bit of code in the parent VI. This is post-release flexibility which can be pretty cool. Shane. Ditto. Only I don't have to change the plugin either See above.

QUOTE (Tubi @ May 15 2009, 01:49 PM) Well the latest example you supplied seems to work fine. I changed the variables on the front panel and it didn't complain. Are you saying that it works in simulation but not on the hardware? If this is the case. It might be useful to capture the data from the machine to a file and run that through the simulation. Then w can all see and investigate the differences.

Sorry Shoneil. We must have been posting simultaneously and I didn't see your post. QUOTE (shoneill @ May 14 2009, 09:32 AM) Actually, its instrument independent. And "hopefully" your instruments have a pre-defined protocol otherwise it really shouldn't be on the market. The idea is not to replace Daklus approach. It's a way I've used over and over again on many projects with many comapnies with many different instruments to alleviate the "Driver Wrapping" which I always see as the ball-ache of not only classes, but programming in general around instruments. It's just a very quick way of incorporating an instrument and configuring it with a minimal amount of coding and total re-use. QUOTE (shoneill @ May 14 2009, 09:32 AM) I have also realised a LVOOP driver for a spectrometer which, while it has a LVOOP Backend running in a parallel process provides an interface via User Events. A spectrometer is pretty much like any other so defining the classes was not too hard. In order to incorporate a new Spectrometer I simply create a new class and feed this into my background process (which thanks to LVOOP runs with the new class without any code changes). Daklu's Idea takes this a step further. If I have understood correctly, you do something similar but then provide a way for broadcasting which Interfaces are available for a device. So I could have my Spectrometer servicing both a Spectrometer and a Colorimeter and a Temperature sensor interface. Is that correct? Is that the idea behind the examples posted? I have to confess I've read the document but not tried out the code. In addition I could jerry-rig a filter wheel (RS-232), a monochromator (GPIB) and a Photomultiplier (DAQ) together to create an Interface for a Spectrometer using three different devices witht hree different protocols. My top-level software doesn't care, it just calls the "Get Spectrum" method and (after a little while for a scanning spectrometer) delivers the data. This is what I see too. The abstraction can be a functional abstraction of the task rather than abstraction of the devices.

QUOTE (Daklu @ May 14 2009, 10:36 AM) In fact. None of them are SCPI. I think your getting hung up on that. I was just making the point that if they are then you can use the same files. Here's some examples from a real project (apart from the 34401 which I added just so we have a common reference.). Download File:post-15232-1242328643.zip Different manufacturers, different command sets, 2 are RS485, 1 is TCPIP and of course the 34401 is GPIB. All I had to do to incorporate them was copy and paste from the examples in the user manuals to the files (and add some comments) and add a couple of entries in the lookup table...Job done. Probably took me longer to find the manuals on our network...lol. QUOTE (Daklu @ May 14 2009, 10:36 AM) I should have said non-VISA driver. The drivers supplied with the 8451, Aardvark, and CAS-1000 did not use VISA. I suppose it might be possible to wrap their driver and make it VISA compatible and SCPI compliant... I did not consider that at the time and even now I'm not sure I'd want to take that bull by the horns. I don't know about those products, but I do know most DVM's, Oscilloscopes, Spectrum Analysers, Drive Controllers, Temperature Controllers, PIC programmers....you name it...generally have (or can be ordered with) a serial (232/422/485) Ethernet or GPIB interface. Regardless, if they don't, you don't have to make them VISA or SCPI compliant. You just have to know the command syntax (user manual or existing driver) and add the hardware interface to the write-read vi. The important thing to note here is that once you do this you can interface to any device on that interface. If you take a look in the bowels of my OPP over bluetooth somewhere on this site, you will see a cut down version in action. Although it says bluetooth, it actually works on TCPIP/UDP, bluetooth and IRDA interfaces since OBEX is a protocol running on a transport layer as is Ascii for instruments. QUOTE (Daklu @ May 14 2009, 10:36 AM) It isn't my intent for the Exterfaces Architecture to be based around a hardware device. That's what burned me in the first place. Interface definitions, like interfaces in text languages, are based on a set of common functions. The IVoltmeter interface can be applied to any device that can measure or calculate voltages: DVMs, oscilloscopes, DACs. It doesn't even have to be a physical instrument. In theory you could implement an exterface that reads current and resistance measurements from a text file and returns the calculated voltage. (Though it would be a bit tricky to implement that in this particular interface definition.) The example I've included happens to have 4 instruments that are fairly narrow in their capabilities and so I can see how it would look as if that is what I was doing. Great! Back on topic Indeed. And this is why I think its far more useful than anything else I've seen in classes based around instruments, which are always peddled as infinite extensibility IF you write 100 similar snippits of code to wrap already existing functions (which is what I thought first of all with yours). Add a new DVM? Write another 20 function wrappers like the last lot only a bit different. But if I use your exterfaces (I think) I can wrap 1 piece of code and use the exterfaces to define higher level function like entire tests. Instead of an IVoltmeter. I (could) have an IRiseTime and choose which subsytem to run it on (for the one to many). Or maybe I'm just barking up the wrong tree.lol. QUOTE (Daklu @ May 14 2009, 10:36 AM) Either one is fine. Some of your earlier comments made me think you might be referring to the exterface as the device driver. I didn't think so, until you put the device driver as an exterface instead of a device driver (as I was expecting). QUOTE (Daklu @ May 14 2009, 10:36 AM) Yep. (Well, not so much enable multiple inheritance as simulate multiple inheritance.) A nod's as good as a wink to a blind man Symantics. QUOTE (Daklu @ May 14 2009, 10:36 AM) None of the instrument drivers I used (as supplied by the mfg) required me to be concerned about the HW transport layer. All three of the instruments mentioned were USB only. I admit it had not occurred to me to be concerned about that. I'll have to think on that for a bit. USB DVM's? Maybe they just supply a lead which is a USB->RS232 converter. QUOTE (Daklu @ May 14 2009, 10:36 AM) I didn't say it was good, I said it's not necessarily bad. I have several small utility vis that I routinely copy and use in projects. Why? Several reasons: If another developer checks out my source code the file will be there and he won't have to worry about finding and installing my reuse library. (This was not a mature Labview development house; it was a bunch of engineers working on (for the most part) quickie tools.) You mean Like not having to download the JKI Test Toolikt eh? QUOTE (Daklu @ May 14 2009, 10:36 AM) I had lots of related vis in that particular .lvlib but typically only used one or two of them. I didn't want to pull the whole library into the project. I tend to store single vi's in directories. Never use libs, and never use LLB's, so this isn't an issue for me or anyone else that uses my toolkits. QUOTE (Daklu @ May 14 2009, 10:36 AM) Managing shared reuse code tends to take a lot of time. Copying and pasting takes very little time. It does? I dind it the other way round, not to mention the fact that you have to to-arrange everything and get all the wires straight again. QUOTE (Daklu @ May 14 2009, 10:36 AM) I disagree. The ideal scenario is where just the right amount of features are exposed and available. Let's say the Ace VM that requires 6 steps to initialize and get into the proper state for a particular application and the CAL VM requires 2 steps. Following the traditional class hierarchy we create an abstract Voltmeter base class and do all sorts of work to create a common command set for two very different APIs that still exposes all of the functionality of each. Then we wrap each of the device drivers in Voltmeter child classes. We've just done lots and lots of work to ensure dynamic dispatching for functions we may not ever use and may need to change when we derive a Delta MM child class. On top of that, what do we do with those 6 steps needed to setup the Ace VM? We undo almost all of our work by wrapping them back up in a project sub vi and naming it Init! Would have been much easier to just implement Init using the original device drivers... And then someone comes along and says "Oooooh. Our Tektronics scope has a really useful feature that enables me to wash the car whilst toasting a muffin. We need that feature too". And you end up doing it anyway or you end up back in your original conundrum where everything is an exception. But you've hit the "nail on the head" and as I pointed out to someone else. OOP in labview make development as slow as the other languages for precisely those reasons when its historically been a lot faster. And it is why you don't want to expose the full feature set of the device when you already have a supplied one from the manufacturer. It takes too damn long. QUOTE (Daklu @ May 14 2009, 10:36 AM) See, I'd use the explicit calls. It would make debugging easier. 'Auto' would be the default though. Your baby, your call. Just means you get a load of idiots like me asking why its not working when they've created instead of linked.

QUOTE (Daklu @ May 14 2009, 02:22 AM) Told you you wouldn't like it The config files have straight strings (no regex). Config files don't extract anything. They are just a way to stream multiple commands to the instrument. A vast majority of instruments (DVM's, Temperatures controllers, drives...you name it) supply an ascii command set for their instruments and they are usually the same commands regardless of HW interface (Wheter it be RS232/485, TCPIP or Bluetooth). If it's someone like Agilent, Keithly etc, then they are SCPI compliant, which means you can pretty much use the same files for similar devices from each manufaturer and you can support any device from them by just peeking at their driver (which is really a parser) and extracting the strings (in fact I have a vi that does that and generates the files from their examples). Non-VISA instrument?. Not sure what you mean by this since VISA is a hardware abstraction (Serial, TCPIP etc). Like I said, 90% of devices use these interfaces. But my particular read-write "tool" also supports CAN, FIP, MVB and STANAG. Once the read write has been "upgraded" you can support any device on those interfaces. "polyconfigurism". Now your just making things up ...lol. I'm just pointing out that it is possible to envisage an abstraction that is not based around the object you are trying to interface to, which tends to make the software specific for those objects, and you end up writing/copying, pasting code for new devices because the abstraction is miss-targeted. QUOTE (Daklu @ May 14 2009, 02:22 AM) My 'application' actually was designed as a toolkit of top-level VIs that would be sequenced using TestStand. (And it would have worked great if it weren't for those pesky design engineers!) The problem is that the top-level toolkit was built on several other layers of toolkits I was developing in parallel. I haven't worked through how to set up the entire architecture using exterfaces instead of the design I did use, but it looks promising. I'm not sure it will help for what you are envisioning. But if your exterfaces are based around the function the engineers are trying to achieve, rather than the devices they "may" be using I think it will work great. But, you know your design, and your target. I've also found that giving the engineers a (slight" ability to affect the software (like my technicians example) means that they end up making the changes and not you QUOTE (Daklu @ May 14 2009, 02:22 AM) I didn't include the device driver itself simply to save space and as far as I know they are freely available. I don't normally include device drivers as part of a project file. Did the project link to your drivers correctly? I can add the driver I used and repost if needed. I don't use the Agilent . so cannot say whether it works or not. But it loaded and compiled fine. I was just interested in seeing how you integrate a previously defined driver in your architecture and chose one that you have. QUOTE (Daklu @ May 14 2009, 02:22 AM) I'm not sure why you expected the 34401 exterface to be listed in the device drivers section of the project. An exterface isn't a device driver to my way of thinking. In this project the interfaces are an abstraction of a particular type of measurement. (Voltage measurements and current measurements.) The exterfaces implement the abstraction for a specific piece of hardware using the device driver supplied by the vendor. The files in the device drivers folder represent the drivers that are supplied by the instrument vendors and would normally reside in <instr.lib>. Because it's a DVM in the same light as your ACE or BAM. I had expected the Agilent to apear in the list of Device Drivers" and a simpler "Exterface" wrapper to interface to the architecure. QUOTE (Daklu @ May 14 2009, 02:22 AM) You lost me. By "Device Driver," do you mean the exterface or the actual device drivers? I was using "Device Driver" as in the context of your ACE or BAM etc since that is where they appear in the project. "Instrument Driver" perrhaps? The exterface (and I may be wrong) looks to me like a wrapper around the "Instrument/Device Driver" to enable multiple inheritance. QUOTE (Daklu @ May 14 2009, 02:22 AM) When you say "a class implementation of my previous example," do you mean a class implementation of polyconfigurism? Isn't the point of polyconfigurism to avoid classes so you can add instruments without writing G code? Can you show me what you mean, maybe by stubbing out a simple example? (Text is fine, or if you're particularly ambitious you could try ascii art. ) I meant a base class implementation the of hardware abstraction. Where you could have (for example) a class that takes the an HW interface (TCPIP,SERIAL etc). And methods such as "Read", "Write", "Configure From File" sitting below your BAM, ACE and Agilient. Your instruments can inherit from that (basically your parser) and your exterfaces would be the equivelent to the alias lookup (maybe). QUOTE (Daklu @ May 14 2009, 02:22 AM) If you restate that as 'copying and pasting in the same project,' I'll agree with you. But I contend copying and pasting code between projects doesn't necessarily make it a good candidate for inclusion in a shared reuse library, especially if you are modifying the code. I view the interface definitions and exterfaces somewhat like a template or boilerplate code. Copy, paste, edit as needed. We agree with copying/pasting the same project. I disagree that copying and pasting code between projects is a good thing if no modification is required. And if you are modifying the code it isn't being re-used so it shouldn't be in a re-use library. QUOTE (Daklu @ May 14 2009, 02:22 AM) You lost me again. Do you mean this is a bad case in the Exterface Architecture class implementation strategy or in the Labview class implementation strategy? Labview. QUOTE (Daklu @ May 14 2009, 02:22 AM) Labview does this too...? Not without changing the overrides (I think) QUOTE (Daklu @ May 14 2009, 02:22 AM) The interface definition provides the application with the appropriate instrument control resolution. At one extreme we have a simple, high-level interface with Open, Read, and Close methods. At the other extreme is a very low-level interface that defines the superset of all instrument commands. Different applications require different resolutions of instrument control. I can't define an interface that is suitable for all future applications, so I don't even bother trying. The small changes I make are simply to customize the interface's resolution for the application's specific needs. Indeed. But the ideal scenario is that all features of all devices are exposed and available, and you just choose which ones to use in the higher level. This was the same problem that IVI tries to address. Just because we use classes doesn't make this any easier. QUOTE (Daklu @ May 14 2009, 02:22 AM) Ahh... I get it. If the developer "creates" an instance using a name that already exists, it would automatically link to the previously created instance. I'll have to think about that. Maybe rename it "Attach" with a three-state enum input for 'Create New Instance,' 'Link to Pre-existing Instance,' and 'Auto.' I'd go for the "Auto" only. Doesn't give people the opportunity to get it wrong then. QUOTE (Daklu @ May 14 2009, 02:22 AM) There's nothing in the architecture that prevents the developer from creating a 5th instance. What happens depends on the instrument and the vendor's device driver. If the instrument is connection-based and a connection has already been established with another instance, the driver will probably return an error. If the instrument is not connection-based then yeah, an inattentive developer could screw things up. Well. There is no reason that the instrument shouldn't give a result from the request, as long as the "object" ensures that the instrument is in an appropriate state to give a correct response. I'm thinking here of....say... you create an "Ammeter" instance and a "voltmeter" instance rather than an "ACE" instance.

QUOTE (santi122 @ May 13 2009, 12:58 PM) Should add that to the obfusification thread...lol.

QUOTE (angel_22 @ May 14 2009, 01:55 AM) http://forums.lavag.org/How-to-Insert-Images-in-your-Posts-t771.html' target="_blank">Inserting Images, vis etc

You don't have enough data points above and below the threshold to complete the "Peak Measurement" analysis. Either 1.Change the "percent level settings" method from "Auto Select" to "histogram" to force that method or 2. Change the threshold levels to something like 40%,50% and 60%

Thats a fantastic name....lol. I have a solution for that....but you won't like it If you abstract the interface, rather than the device, you end up with a very flexible, totally (he says tentatively) re-usable driver. I'll speak generically, because there are specific scenarios which make things a bit more hassle, but they are not insurmountable. Take our ACE,BAM and HP devices. From a functional point of view we only need to read and write to the instrument to make it do anything we need. I'll assume your fictional DVMs are write-read devices (i.e you write a command and get a response rather than streaming) and I'll also make the assumption that they are string based as most instrument we come across are generally. Now.... To communicate with these devices we need to know 3 things. 1. The transport (SERIAL/GPIB/TCPIP etc.) 2. The device address. 3. The protocol. Visa takes care of 75% of No.1. No.2 is usually a part of No.3 (i.e the first number in a string). So number 3 is the difficulty. So I create a Write/Read VI (takes in a string to write and spits out the response...if any), and I will need an open and close to choose the transport layer and shut it down. I now have the building blocks to talk to pretty much 90% of devices on the market. I'll now imbue the read/write vi with the capability to get its command strings from a file if I ask it to. So now, not only can it read and write single parameters, I can point it to a file and it will spew a series of commands and read the responses. This means I can configure any device in any way I choose just by pointing it to the corresponding config file. New device? New config file. No (labview) code changes so you can get a technician to do it Now, in your application, you have a lookup table (or another file) which has a name (alias), the transport, the address, the config file and/or the command for the value you want to read.(....say DC:VOLTS?); The read-write file vi is now wrapped in a parser which takes the info from the table and formats the message and sends it out through the read/write file vi or it loads the config file. I now have a driver scheme that not only enables me to add new devices just by adding a config file and an entry in the table, but also enables me to send the same config to multiple instruments on different addresses or different configs to the same devices on different addresses and read any values back I choose. And all I need is 1 VI that takes the alias. Told you you wouldn't like it because OOP programmers start frothing at the mouth as soon as you mention config files...lol. But I'll come back to this in context a little later on. If your system is such that you only have to code for exceptions. Then you are winning. If anything is changing rapidly, then any software "architecture" is bound to be compromised at some point and the more you try to make things fit...the more they don't...lol. If its for internal use only, you are better off with a toolkit that you can throw together bespoke tests quickly - something Labview is extra-ordinary at doing. Amen. <cite>QUOTE (Daklu @ May 11 2009, 02:21 AM) [/post]</cite> It's damn hard to design a good class hierarchy that will fit all future (unknown) needs--much too hard for me and my little brain. Agreed (apart from the little brain bit). But there does seem to be a lot of "do it anyway" mentality about. <cite>QUOTE (Daklu @ May 11 2009, 02:21 AM) </cite> With those lessons in mind I started mulling over ways to implement interfaces in LabVIEW, which would have (I believe) made my development task much easier. Exterfaces is the result. I created it specifically for engineering tools with the understanding that more flexibility requires more coding. As a matter of fact, for many reasons I'm starting to favor exterfaces over traditional interface models--at least for hardware applications. To be honest I'm not really sure if there's much value in using exterfaces in finished product applications; if the requirements are known you don't necessarily need the flexibility exterfaces provide. OK. Well lets look at your "exterfaces" in the light of the Agilent example that you kindly provided. I noticed that you didn't put it under "Device Drivers" which I hadn't expected and is why I asked for a driver (although typical of drivers) that didn't fit nice and snugly with the simulated ones so I could see how this worked. From your exterfaces up, everything is hunky-dorey (as it always is with classes in labview) and your implementation seems to overcome a big drawback of the current Labview implementation. But this is what I was looking at. If the exterface is higher up in the tree (lets take the previous example of a Waveform test). Which is an exterface based around defining a sequence of operations (Set this, set that, wait 1 second then read result). We can instantiate that with different arguments and do different tests with methods such as "Start", "Abort", "Get Status", "Get Result etc, etc. If we now have the same test, but you need to move a motor into position, set some digital IO, wait 1 second and read the result, then your exterface can be implemented to do that in the same way that you implemented the HP driver, but the underlying method is transparent from the application AND you can have the same test running on different devices. There is value added to the extra coding since you would have to do that anyway in classic labview. Now. If your "Device Driver" was based on a class implementation of my previous example with all those obnoxious classical techniques with files and whatnot, the exterface now just defines the sequence of operations, the files (or class alternative) to configure, and the order of the aliases (or class alternative) to retrieve the result. Then you would have an implementation, that can instantiate multiple tests/measurements on multiple devices with different configurations. I'm sure you could find a way of incorporating this better than I've described, but this my current thought process. <cite>QUOTE (Daklu @ May 11 2009, 02:21 AM) </cite> Regarding reusing exterfaces across projects... depends on what you define as "reuse code." I expect I might do a lot of exterface code copying, pasting, and modifying between projects. If you consider that reuse code then I'm right there with you. Given point 2 above, I'm in no hurry to distribute interface definitions or exterfaces as shared reuse code. Getting it wrong is far too easy and far, far more painful than customizing them for each project. Lots of copying and pasting means that you haven't encapsulated and refined sufficiently. I think this is a particularly bad case in the class implementation strategy which forces you to do this over traditional Labview which would encapsulate without much effort. After all. In other languages, changes to the base class effect all subsequent inherited classes with no changes whatsoever. <cite>QUOTE (Daklu @ May 11 2009, 02:21 AM) </cite> If you're going to reuse interface definitions, not only does the interface definition need to be a superset of all project definitions, it needs to be a superset of all future project definitions. Like I said earlier, my crystal ball isn't that good. (If yours is turn off the computer and head out to the horse track. ) Releasing new versions of reuse code adds a lot of overhead. I found maintaining backwards compatibility can be a huge time sink. Regression testing can be difficult. The api can get very messy. You also need to implement the new functions in all the child classes to make sure your new ideas are workable. Then you have to worry about distribution and, if you distribute the new reuse code to deployed systems, system level testing. That's a lot of mundane and, IMO, unnecessary work. True. But if the definition is broken down into manageable chunks (think of my toolkit comment earlier). Then adding new "tests" doesn't become an issue. <cite>QUOTE (Daklu @ May 11 2009, 02:21 AM) </cite> However, if you keep the interface definition and exterfaces on the project level they don't have to be huge monolithic structures. You define the interface based on what that application needs--no more. There's no need to wrap the entire device driver because chances are your application doesn't need every instrument function exposed to it. If you have to make a change to the interface definition there's no worrying about maintaining compatibility with other applications. Small, thin, light... that's the key to their flexibility. Lots of small changes as opposed to one big change? I'd rather not change anything but I don't mind adding. <cite>QUOTE (Daklu @ May 11 2009, 02:21 AM) </cite> See above. You only wrap what the application needs, not the entire driver. For example, in the Exterface Architecture project the Ace Ammeter device driver can be set to measure AC current only, DC current only, or AC+DC current. However, my application only requires DC current measurements. My IAmmeter interface doesn't define a "Set Measurement Mode" vi because the application doesn't need it. I put the Ace ammeter in the correct mode in XAce Ammeter:Open and don't worry about it after that. I think this means (in my case) that you end up with lots of applications that can do very specific tasks with very specific hardware. <cite>QUOTE (Daklu @ May 11 2009, 02:21 AM) </cite> "Create Instance" creates a new instance of the device driver and links that exterface to it. "Link to Instance" links an exterface to an already created instance. An exterface will use one or the other, not both. Use "Link" when an instrument is going to use more than one of it's functions. The vi "Many to One Example" illustrates this. (Look at the disabled block in "Init.") The system has a single Delta multimeter but it is used to measure both current and voltage. If I create two instances I end up with two device driver objects referring to the same device. That leads to all sorts of data synchronization problems and potential race conditions. By having the second exterface link to the same device driver object the first exterface is using, those problems are avoided. [Edit: Your question made me realize "Create Instance" and "Link to Instance" aren't good names for developers who are using the api and aren't familiar with the underlying implementation. "Link to Instrument" works, but "Create Instrument" doesn't. Any ideas for better names?] I've no problems with "create" (that's the same in other languages or you could use "New" as some do). But I can't help thinking that the linkto is a clunky way to return a reference to an object. If the "Create" operated in a similar way to things like queues and notifiers where you can create a new one or it returns a reference to an exisiting one, it would save an extra definition. <cite>QUOTE (Daklu @ May 11 2009, 02:21 AM) <a href="index.php?act=findpost&pid=62740"></cite> Suppose you have more than one Delta multimeter in your test system. On the second "Create Instance" call should it create a new instance for the second device or link to the first device? There's not really any way for the software to know. Seems to me requiring the developer to explicitly create or link instances makes everything less confusing. Rereading this I realize I didn't make one of the exterface ideas clear. In my model, each instrument has its own instance. Ergo, if I have four Delta multimeters in my system then I'll have four instances of the device driver object. If the device driver is not class based (such as the 34401) obviously there aren't any device driver objects to instantiate. In those cases the "instance" is simply a way to reference that particular instrument. Since all calls to the 34401 device driver use the VISA Resource Name to uniquely identify the instrument, I put that on the queue instead of a device driver object when XAgilent 34401:Create Instance is called. This allows the 34401 exterface to behave in the same way as exterfaces to class-based device drivers. Indeed. But having created 4 objects already, what happens if you create a 5th?<p>

QUOTE (normandinf @ May 13 2009, 03:07 AM) Awwww. Don't feel left out. Feel smug in the fact of knowing that they will find all the bugs first so that when you upgrade to 2009.1, it actually works

Its better to post in this forum. Then others may learn from the questions and answers.

QUOTE Right click on the property node and choose "Change To Write" from the menu. QUOTE Also, how do I unpack this on the Block Diagram? If I attach an "Index Array" VI with no index (to indicate I want the first element of the array), the output data type is an array of one element, which is not what I would expect. I would expect a cluster of one WaveGraph. It should be a cluster containing a 1D array. If you put a Waveform graph on your front panel then right click and "create" constant on the diagram. You will see it creates a 1D array of Double Precision constant.This is the default format. You can see more on the input options in the help for Waveform Graph (a 2D Array is a multi-plot for example).

QUOTE (Ton @ May 12 2009, 09:13 PM) can you not do it by the plug-in name? (therefore avoid loading anything)

Most PC's have DACs and ADCs built in nowadays.....Your sound card. If your looking for cheap!.

QUOTE (angel_22 @ May 12 2009, 12:46 AM) A good starting point might be the temperature system demo in the examples directory. It demonstrates alarm (over temp, under temp) detection and would at least provide a frame of reference for you to ask specific questions.

QUOTE (Ton @ May 12 2009, 06:47 PM) Sorry, I'm not. Not quite sure what difference it makes if the open file ref is in a splash-loader or not, but, I also have a "cleaner", which goes through all the vi's, loading them and identifying orphan files. That only takes a couple of minutes to load and check every vi. So I'm still a bit baffled.

QUOTE (Neville D @ May 12 2009, 06:22 PM) .....And no more compatible file-system.....no more 3rd party support. LV-Rt is only a real option if your system is completely NI based. QUOTE (rolfk @ May 12 2009, 08:10 AM) Which makes it probably more like XP Embedded anyhow Rolf Kalbermatter Shhhh. Don't tell everyone

QUOTE (Ton @ May 12 2009, 05:58 PM) This seems a bit bizarre. My whole application (a couple of thousand vi's) only takes a few seconds to load (via an open ref then run from a splash-loader). Why does it take yours a few minutes to load a vi? Does it have to search for sub-vi's?

QUOTE (crelf @ May 11 2009, 09:46 PM) Indeed....lol. We don't rely on it, safety critical aspects are hardware enforced (like E-STOPS which will cut power and air at the supply), Like I said though. Windows is very robust as long as you don't have all the other crap that your IT dept would put on, disable all the unwanted services, don't use active X or .Net and only run your software.

QUOTE (Michael Malak @ May 11 2009, 10:08 PM) You used to be able to put graphs directly into arrays.I don't think you can anymore. But you can do this...... http://lavag.org/old_files/monthly_05_2009/post-15232-1242078686.png' target="_blank"> Put your graph into a cluster. Then put the cluster into an array.

QUOTE (crelf @ May 11 2009, 07:25 PM) Actually. We can and we do. We specify the PC in detail. From the processor, motherboard, chassis, drives etc to RAID10, cooling and vibration/shock resistance. We also stress test the machines for 1 month before delivery. Whilst we can't prevent hardware failures, we can limit the impact on production with considered choice and preventative maintenance. These aren't laptop/desktop pc's loaded with word, excel and all the other crap. These are purpose built production machines, (designed to run 24/7 and come with a 10 year life expectancy and 5 year warrantee) which have only ours and national instruments software (apart from the OS and drivers). So if there is a software "fault" there is no-one else to blame. If the operator is capable of breaking it. Then we haven't designed it properly. QUOTE (crelf @ May 11 2009, 07:25 PM) If the user ignored a "improper shutdown, hard disk has errors, run scandisk" message and your software faults due to that, is that your fault too? Yes. The operators function is solely to load/unload the machine with parts, start the machine in the morning and stop the machine at the end of the shift. No more is expected. If an error is detected in the software, it sms's us with the error and we contact the customer to ensure that preventative action can take place on the next shift changeover. QUOTE (crelf @ May 11 2009, 07:25 PM) I'm not saying that you can't plan for these things, but you have to, well, plan for these things. If you know that you need to activate Windows in 30 days or it'll bomb out, then you activate Windows within 30 days so it's okay. You need to gain and apply that same level of product knowledge to all the components you apply to the system - including anything from NI or any other manufacturer. That said, if a user ignored an error for a month (whether that be from an activation issue or a hard fault) and then expected me to fix it immediately once it bombed out, I'd be having a stern talk to them. errrrm. I didn't think it was in question that the OP (or myself) hadn't originally activated Labview. He was talking about the fact he had activated it and after an update Labview required re-activation. We have an OEM license for windows so activation isn't an issue (if we decide to use windows that is, we also use linux so activation would be irrelevant). Any (and I mean ANY with a capital E) errors must stop the machine and turn it into a paperweight, otherwise people can lose limbs. We have no issues with windows (it's remarkably stable, if you don't load it up with active X or usual rubbish you find on a desktop PC) and we have had only 2 windows failures in 4 years both due to malicious intent. Windows has never suddenly popped-up that it requires re-activation. Or refused to work because of licensing. However, as I pointed out, we have had 2 instances as of this year so far of Labview requiring re-activation.

a description of your problems would be helpfull. Perhaps some pictures of the code you have already?