buffered counter acquisition compact DAQ

[jgcode]

[cross-posted to LAVA] http://forums.lavag.org/cDAQ-Buffered-Counter-Acquisition-t13728.html

Hi

I am trying to setup a buffered counter acqusition (correlated) using compact DAQ.

Hardware:

cDAQ 9172 chassis

Slot 1: NI 9237 (AI Bridge used as an external timing source only)

Slot 5: NI 9411 (High Speed DI TTL) I have to use the extra module to export it's clock as I am using the internal counters in slot 5.

Please see cross post for pictures 

1) Is this hardware compatiable?

2) If so, any suggestions on how to get this to work as I am having trouble running it.

I use the following parameters which works fine for an On-Demand sampling - it reads back the expected value from the sensor.

[attachment=11616:parameters.PNG]

But when I switch to Continuous the I get a timeout error.

[attachment=11615:realError.PNG]

However, if I use simulated hardware through MAX I don't get an error and the buffer fills on the screen.

Any ideas?

Regards

JG

Message Edited by jg-code on 04-03-2009 04:06 AM

Message Edited by jg-code on 04-03-2009 04:07 AM

Message Edited by jg-code on 04-03-2009 04:07 AM

[Chris_W.]

Hello,

An external sample clock must be used.  Counters do not have an internal sample clock available. You should be able to use another timing source from your ai or ao task. This is definitely a case where your linear encoder task is not seeing the sample clock that you are trying to apply to it. When you are using the aSample Clock, do yo actually have an AI task running at the proper frequency? There will be no AI sample clock if you do not have an active AI task running.

You can also use the Gen Dig Pulse Train-Continuous example to generate a pulse train on another counter and connect it to the Sample Clock Source you are using in this example. If you try this out and physically connect the output of the pulse train generation to the input of the encoder task, does that take of the buffer problem? 

Chris W