labview FPGA - CRio 9073 - CRio 9205

[chouca]

Hello,

I begin with Labview FPGA and try to read AI channel on cRIO 9205.

I've created a project, add my FPGA target (cRio 9073) and "slide" the module 9205 below FPGA target to have access on this module.

Then I've copied the FPGA Vi found in the example "NI 9205 basic IO" and compiled it.

Then I've opened in my RT VI a FPGA VI reference and have accessed to the inputs/outputs defined in the FPGA Vi.

The problem is that I can't read the real values on the analog inputs of NI 9205.The values I've read seem to be simulated (a sinus between -10V and +10V)

I notice I am in evaluation mode for FPGA (may it be the reason?) and I have checked in FPGA target option (right click on it) my FPGA VI run on FPGA target and not on development computer with simulated values.

Thanks. 

[Robbob]

Chouca,

It sounds like you have done everything correctly. The FPGA module being in evaluation mode makes no difference, you get full functionality for your 30 days. You have also verified that you are executing the VI on the FPGA. Are you using the provided host VI as well or one you created? have you tested the digital lines of this module to verify that they work as well?

I know this seems to be a silly question...but do you have anything connected to the signal inputs? If it is an open connection, the readings will float to -10 or +10 volts.

[chouca]

Hello,

Thanks for your answer. I had my connection open on the input by mistake.

I have another question about using Scan engine or Labview FPGA interface.

My project is to acquire measurements of voltage (CRIO 9205), current (CRIO 9203), temperature (CRIO 9211) and counts (CRIO 9401).

I have to manage about 76 channels, store the data on the RT target (CRIO), with a quite low sample frequency (~10Hz). I have to change the sample frequency if the measurements are above a threshold (trigger).

I try the 2 modes (Labview FPGA interface annd Scan engine) and the Scan engine seems to be easier to use. But in this mode (by reading the channels with shared variables), how to configure the voltage range, the type of connexion (RSE, differential...), detect a trig? And what is a good way to store data on the RT target (write a TDMS file on the target?).

Thanks.

[Robbob]

That's more than one question!

I try the 2 modes (Labview FPGA interface annd Scan engine) and the Scan engine seems to be easier to use.

For sampling rates of 10hz, scan interface mode will be sufficient.

how to configure the voltage range, the type of connexion (RSE, differential...)

These can either be changed in the project(right click on module->properties) or at run time using a property node. Drag the module from the project to your block diagram. You should get a reference constant named 'ni.var.io//crioname/mod1'. Drop a property node onto the block diagram and wire this reference into it, and you will have access to channel properties.

detect a trig?

Make a case structure 'if voltage >x, then log data'. If you want pretrigger samples, store them in a shift register until you need them.

And what is a good way to store data on the RT target (write a TDMS file on the target?)

File IO on a cRIO works exactly like it does on a windows machine. you can use all the TDMS functions and examples we provide. c: is the flash memory on the cRIO. You can then FTP into the controller and retrieve the data, or use tcp/ip to pass data to a windows host, or since this is such a slow speed, you could pass all data through shared variables to a windows computer.

Message Edited by Robbob on 01-19-2010 08:17 AM