French LVer

Tested on an Intel Pentium M 1.7 GHz 512 Mo.

For 10 FFT

=> LV 7.1 : 126.5 to 128.2 ms

=> LV 8.2 : 143.6 to 145.0 ms

Might be better on a real computer

As sonic_raajit said, settling time is very short.

You must have some side-effect problem.

You should consult "E Series User Manual" page 2-9 to 2-13 (Multichannel Scanning Considerations).

You can find this manuel here : E Series User Manual

I hope it will help you.

QUOTE(Jeff Plotzke @ Feb 27 2007, 02:12 PM)

So, to make sure I understand completely, I should be able to run control on both valves in parallel, using a P-controller on the coarse valve, and a I-controller (perhaps with a very slight P) on the fine valve. Correct?

Yes Jeff. One PID for each valve in parallel :

- Coarse valve PID with a "loose" P (in order to avoid resonance).

- Fine-tune valve PID with neat set of PID (in my case, I-parameter is doing all job).

QUOTE(crelf @ Feb 27 2007, 01:54 PM)

That is indeed a valid control molel :thumbup: , but I don't completely agree with the first of your two "facts": it should work irrespective of the speed of the SP - it's actually the speed of the response of the system to the P control.

It depends if you need a fast response on a 0 - 100% command. P regulation is loose and I regulation is only on fine-tune valve.

Greetings,

I guess i will be OT once again but i use sometimes regulation with two valves.

Regulation chosen is based on these two facts :

- setting point changes slowly,

- and controlled system is quite stable.

So i use a loose proportional regulation loop (no I and D) for coarse valve.

And fine-tune valve do all regulation job (with mainly integral).

This way, there is no need to switch between several settings.

Bye.

Greetings yannis,

I can see two ways to measure digital timings with usb 6009.

USB 6009 has a counter input that will help you determine delays between switchings. Unfortunately, there is only one counter input on your device.

The other way is to use free analog inputs to acquire digital signals.

I hope that will help you.

Greetings Eugen,

You just need to edit your function palette.

On LV 7.11, it is in "Tools -> Advanced -> Edit pallette 's type". Then you right-clic on icon to be moved and select "move this sub-menu".

I'm not sure about LV 8.0 but it must be nearly the same. (I have a french version of labview so my translations could be false).

Good luck

Hi,

Just some hints for you kbllau.

You will have to create a timed loop or a while loop with a timer set to 2 seconds. In it, you will read values of 5 controls from front panel and write them in a table from database.

Good luck

Thank you for your quick reply Syd,

Your solution imply a second daq board in order to acquire low frequency data.

Perhaps, i could use a very slow daq system using RS232 for duplicated signals.

Your answer helped me in clearing ideas. Thanks again

Greetings from France,

I'm almost new on LAVA forum and i already need your help

I'm currently on a software specification (coded in Labview) using data acquisition.

Briefly, i have two daq processes running in same time on same channels :

- a polling acquisition (one sample per channel) recording 16 channels each 10 minutes,

- and a continuous acquisition (11 channels at 1kHz each) triggered by a digital input's edge front for 10 seconds (retriggerable).

My question is :

- Is there a way to disable polling acquisitions when daq card is currently working on a continuous one (by reading daq card activity for example) ? I assume NiDaq's error will occur if both actions are asked to daq card.

If it isn't possible, i will have to continuously acquire all channels at 1kHz (analog and digital) and do triggering action by software.

Without daq hardware available right now, i can't test it by myself so i ask you all for some advice :worship:

I know this is not really relative to Labview but you might have encountered it on your own applications.

Hi,

There are many ways to solve your problem.

I hope attached image will help you

PS : oops JFM posted faster than me

Hi,

In order to test your database link you can use this little sample. I use MySQL database.

First, you must have created a database ( CREATE DATABASE `MyDatabase` ; ) and made an UDL link.

This sample create a table, insert two rows, read all data and destroy it.

If you still have link problem, we will be sure it will be access rights

Download File:post-6860-1164957361.zip

Hi,

I tested "DB Tools List Tables.vi" in order to check your problem. (I'm using LV 7.1.1)

In my Access database, table referenced at index 0 doesn't really exist. It seems to be a metabase.

So i think you must access first table of your database with index 1.

I hope that solves your problem

Hi, i'm new on this forum but i think i can help on your problem

I think you can use time-out option of Event Structure.

You can see an example on the picture attached.

Best regards