cRIO and ni 9234 modules not working or communicating through fpga with accelerometers, fpga connected to real time application which is also connected to shared variables linked to modbus slave

[jasonh]

Hi,

I have a compact rio which has a 4 way chassis attached to that chassis is three ni9234 modules they are linked using fpga to a real time application then using shared variables in the low speed loop that are linked to a modbus slave to communicate with dcs, the ni 9234's have accelerometers connected to them with iepe ac coupled option on the c modules, my problem is the real time application seems to be running okay even when power loss occurs it restarts with no problem and the fpga writes to the portable hard drive bin files fine but without a accelerometer connected I get low noise readings as soon as I connect a accelerometer to any one of the 10 outputs it just goes to a fixed number (0.03125) as soon as disconnect it again it reverts back to reading noise, I have run a scan on the modules and only get a spike when I connect or disconnect the accelerometer, I have tested the voltage at the pins of the module and I get 22 volts dc which makes it more likely that the hardware is not the problem but a software is maybe causing this to hang-up, I attach project and files for your perusal. I also carried out a new project which in scan mode directly linked the module input to shared variable and the same scenerio again. Help would be much appretiated. 

Many thanks

Jason

[preston_johnson · Accepted solution]

Whren using waveform acquisition with the 9234s we recommend the following FPGA and RT template.

http://sine.ni.com/nips/cds/view/p/lang/en/nid/209114

it can be extended as a data logger with:

http://zone.ni.com/devzone/cda/epd/p/id/6388

or using shared variables combined with scan engine

http://zone.ni.com/devzone/cda/tut/p/id/9851

The FPGA in all of these, as well as the RT framework have been used successfully by 1000s of users.  I would recommend giving these a try.