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Porter

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Everything posted by Porter

  1. I thought that it would be nice to extend the muParser library's functionality to include automatic CVT tag lookup. This means that if you input an expression that contains CVT tag names as variables, their values will automatically be substituted during eval. This new CVT expression parser IS AN expression parser. So I tried to make a child of the mupExpr class. Who's silly idea was it to pass this class by reference?! LabVIEW doesn't support dynamic dispatch on class DVRs. So I've re-worked the mupExpr Class to wrap only the muparser handle (hParser) in a DVR. This gives a similar protection as wrapping the class in a DVR but allows us to pass the class by value instead. If anyone objects to this change, please shout out now before I commit changes to github. The code is attached, with an example: NICVT Expression Test.vi You need to install NI Current Value Table v.3.3.0 before opening the project. NICVTExpr.zip
  2. Since your input registers are contiguous, I would suggest reading all of them with one call of read input registers. See attached. Modbus Read Waveform.vi
  3. How much data are you transferring? For example, if you are reading 1000 input registers, one register at a time, then you can't expect to get a sample rate of 100ms. Screenshots or sample code would be useful if you are looking for help. Are you using the Modbus Comm Tester?
  4. Just in case anyone is still interested, the source is now available on github: https://github.com/rfporter/SET-Toolkit
  5. It should show an error on every subsequent read... but it doesn't: It just keeps going as if nothing is wrong.
  6. His code has not fixed the issue yet. It does catch the error, as did Plasmionique Modbus Master, but it is up to you to catch the error and reset the connection. If you don't reset the connection, this can happen: Yikes! No errors being reported and read register 0 is returning the value for register 1. Tanner's proposed fix works. I implemented it in the Plasmionique Modbus Master. With it you can have multiple pending transactions. The responses will be matched up with the requests using the transaction ID. TCP Test.vi
  7. Hah. I didn't see that. I was looking somewhere else. But anyway, I don't see a case where you would only get a LF. In the ASCII protocol, a lone LF should never be sent within the message. And if, for whatever reason, a bit flips to make an LF, then hopefully the error would be caught by failing the CRC check.
  8. For comparison, I copied the CRC calculation from the modbus spec. It's slightly faster (when run on my computer) than your method. I'm not exactly sure why though. And it uses less memory (512Bytes for LUT instead of 131kBytes). crc bench.vi CRC16_Modbus.vi
  9. It is thread safe as long as you use the same instance of serial master when communicating with multiple slaves on the same bus. I finally took a look at the code. I have a couple comments/questions: Serial Shared Components.lvlib->Configure Serial Port.vi: Case structure for number of stop bits. I suggest having some override for this. Maybe have a property node for the stop bits setting. I've come across a number of situations where I have needed RTU with no parity and one stop bit. RTU Data Unit.lvclass->Calculate CRC.vi: I think that there is a more efficient way to calculate the CRC using a lookup table. I'd be happy to share it when I get around to implementing it on Plasmionique Modbus Master. Serial Shared Components.lvlib->Serial Read.vi: I don't like the idea of polling the bytes at port every 8ms. Why not just read the specified number of bytes and let VISA handle the timeout? Serial Shared Components->Serial Read to CRLF.vi: Why not just read until LF (let VISA read take care of this)? ASCII Data Unit.lvclass->Read ADU Packet.vi: Why is start character written to request unit ID of Serial Data Unit? Shouldn't it be the unit ID? IP Data Unit.lvclass->Read ADU Packet.vi: Transaction ID mismatch will discard the packet. What will happen on a noisy network connection with multiple transactions being sent out? See: https://github.com/rfporter/Modbus-Master/issues/1 Why does TCP Master/Slave need Protocol Read to CRLF.vi? TCP_NODELAY.vi: Cool... Was this ever used & tested?
  10. I actually still use the OpenG ini library for a lot of my config files. As I recall, it's output was a bit more human-readable compared to the MGI ini format. Recently I've started to look at TOML as a possible replacement: https://github.com/erdosmiller/lv-toml Of course JSON or XML could also work very well but they look a bit more intimidating to the non-technical user.
  11. Plasmionique Modbus Master cannot act as a slave. NI Modbus Library contains a good slave for testing purposes: https://github.com/NISystemsEngineering/LabVIEW-Modbus-API
  12. At the time, I was using the actor framework for a large project. I had multiple com ports and multiple devices on each com port. I decided to have an actor per device. Each modbus device actor would build its own modbus instance from the device's configuration file. Since the modbus instances were thread safe, I didn't have to worry about sharing a com port with multiple devices. Devices on the same com port simply wait in a FIFO queue for the port to be available. I could have instead implemented a modbus master actor and spun up one of these actors per com port. The device actors would then have to send/receive their modbus data through the modbus master actor running on their com port. This way, the modbus master library doesn't need to be thread safe (in terms of shared com port), but I found that it added an extra layer of complexity. I prefer to handle serial communication in my hardware abstraction layer rather than my application layer. Otherwise the device's driver would be tied to the actor framework and would be difficult to reuse for other projects
  13. NI Labs Modbus API is now on GitHub! Password protection of VIs has been removed. https://github.com/NISystemsEngineering/LabVIEW-Modbus-API
  14. The idea would be to include the LAVA CR except for non-vip packages and the uncertified section. On LAVA, we used to submit our code to the uncertified section first. Then after some discussion, testing, debugging and polishing, we would report to the moderator that our code is ready to be certified and placed in the appropriate category in the CR. I'm not sure if this is being enforced anymore. The how-to is from 2009:
  15. I think that when a package is hosted in multiple repos, VIPM displays the entry from the most recent package version. So if you release a new version on the LAVA repo, it will show up as an update for the LVTN version. This is definitely not what we want to do. A solution could be to make separate LAVA and LVTN packages. For the LAVA package, you could append _LAVA to the product name and have the LVTN package listed as incompatible. For the LVTN package, have the LAVA package listed as incompatible.
  16. First of all: Thanks for sharing! Do you plan to implement array slice syntax at some point? For example, $.MyArray[5:20] would return elements 5 to 20 of MyArray.
  17. The projects that I post on LAVA are typically developed on my spare time. They are solutions to problems that I encounter at the office but don't have time to work on during office hours. I post them here because this community is home to some of the most competent LabVIEW architects. What better place to get a decent LabVIEW code review? The result is very good code but not quite polished enough to pass the tools network requirements. The extra time and effort to bring the project through the tools network certification process is just not worth it for me. I'm not making a product for sale. It would be nice though to share these projects with a wider audience. Perhaps in a later version of VIPM, JKI could consider adding support for the LAVA repository (if/when it exists) in their free version. Maybe have an enable checkbox hidden away in a config window. Once enabled, they can display a big warning about how code from LAVA doesn't go through the same certification process as JKI and LabVIEW tools network.
  18. Wouldn't it be nice to have a public LAVA repository for VI package manager? I'm not sure how to make this happen. Just throwing the idea out there.
  19. This is fixed in the latest version (v1.3.3.1) here:
  20. Is anyone interested in releasing an open source Modbus server for Labview?
  21. In version 1.3.2 the session valid property of the MB Master TCP class was broken. This is fixed in v1.3.3.
  22. A little bit more testing and tweaking is required. Almost ready for another release though. Here is the preview: mb_master-1.3.2.7.vip Transaction IDs are randomly generated.
  23. I have implemented transaction IDs for Modbus TCP in the "Transaction ID fix" branch here: https://github.com/rfporter/Modbus-Master/tree/Transaction-ID-Fix Could use some feedback. Here is a vip if you would like to take it for a spin: mb_master-1.3.2.4.vip
  24. I will look at adding it to the next release. I also want to add polling of holding registers and coils as an option in the Modbus Comm Tester. I also plan to properly implement transaction IDs for Modbus TCP: https://github.com/rfporter/Modbus-Master/issues/1
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