EtherCAT 9144 and cRIO

[TinoMK]

Hi all,

I have the following configuration: cRIO 9022/9114 with couple of 9239 modules and I need to expand the channel number with additional 9239 modules via 9144 expansion chassis.

Can anyone sugest some examples on how to read simultanioulsy data from AI channels from both my cRIO and 9144?

Thanks,

[crossrulz]

What rates are you trying to read at?  The EtherCAT communications only work with the Scan Engine on the cRIO and you have to create a variable for each measurement channel you want.  This means that you can only get a sample about once every 1 - 10ms.

How many channels do you actually need?  What are you doing with this data?

[TinoMK]

Hi crossrulz ,

Thanks for the reply. This is my applicaiton:

It is a SHM systems using 9239 and cRIO as platform. I might have a situtaion where I need more than 32 channels (8 slots x 4 chanles form 9239) for example lets say 32 + 4 total of 36 channels. I would like to use 9144 expansion chassis for additional 9239 modules. My sampling rate is 1Khz for all channels. ( i.e. 1000 samples per second per channel)

I know that I need to use variable for the measuremet but it is not clear how to use that and reuse my acqusition code (both FPGA and RT).

How to program the FPGA on 9144? How to synch that FPGA with the main one on cRIO? And finally how to read data in my RT code? Now I use one DMA to transfer my data form main FPGA to RT.

Thanks again, 

[crossrulz]

The 1kHz will be pushing the limits of the scan engine for sending data to the cRIO.  And if all you are doing is just reading the data, then you don't really need to program the FPGA.  Just use the Scan Engine.

The EtherCAT module is just added on to the cRIO in the project (right-click on the cRIO and select Add Target or something like that).

[TinoMK]

Use the Scan Engine in my RT part or use ot on the FPGA part of the cRIO?

Also If I want to program the FPGA on the 9144 how the two FPGA communicate with the RT part?

Thanks,

[TinoMK]

 In other words I would like to use the FPGA on the 9144 chassis. I might have full 9144 chasis with 9239 modules and would like the local FPGA to do that job.

How do I merge the data bwtween two FPGA's and use the same DMA as before and leave my RT code unchanged?

Is this possible?

Thanks,

[crossrulz]

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TinoMK wrote:

How do I merge the data bwtween two FPGA's and use the same DMA as before and leave my RT code unchanged?

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There is no DMA from the EtherCAT.  Like I said, you have to use User Defined Variables to get data from the EtherCAT chassis to the RT system.  There is no direct FPGA to FPGA communications.  The User Defined Variables are created in the project.