Module 9870 for reading 4 serial devices...

[Hector D]

Hello,

I want to use the 9870 Module with the cRIO 9022 to be able to read 4 diferent serial devices. Is this possible? If so, do you have a VI that can handle the 4 devices??  The example you have can handle only one port.

Thanks,

Hector.

[ColeTrain]

Hector,

Is  this example you're referring to the one in the example finder?  That example will not work on the FPGA because it is designed to use the serial ports on your computer.  If you found something on IPNet, you can just take the code and copy each loop.  You will only have to direct the FPGA I/O reference to each one of the serial ports.  If you haven't found something on IPNet, try these out.

[Hector D]

Hello,

I looked at the example, but it actually does not work for me as I want to use the NI 9870 module which is a 4 RS232 serial module and the cRIO I'm using is the 9022. The example just uses regular digital I/O. Is there any example on that shows how to use the 4 ports of 9870 at the same time and usign different baud rates for each port??

Thanks,

Hector.

[ColeTrain]

Hello Hector,

I am sorry I pointed you to an example that wouldn't help you.  To configure the serial ports you can just drop an FPGA I/O point on the block diagram.  Each I/O point has a variety of properties to it as shown in the picture below.  You can place multiple loops down to talk and listen to each port on your 9870 independently.

 

Message Edited by ColeTrain on 05-11-2009 12:38 PM

[Hector D]

Hello,

Do you have an example showing how to set up and use the 4 ports?

Thanks,

Hector.

[ColeTrain]

No, sorry.  There is one in the example finder that is a loopback test.  This is the only example I have found.  You might have better luck posting in a cRIO forum, but I have not been able to find anything myself.

[dskrabacz]

Hi,

I am dealing with the CompactRIO 9074 and I have connected the 9870 up to this chassis. I am using the example virtual instrument that was recommended from James. I was able to input all of my Read_FIFO and Write_FIFO with my specific ports, and have modified the ports. When I run the FPGA program, it initializes to step 7, and then exits with the following error message: "Too many DMA channels have been requested or some requested are conflicting. The current target has 3 DMA channels." Does anyone have a fix for this? Thanks.

-Daniel Skrabacz

[dskrabacz]

Hi,

I am dealing with the CompactRIO 9074 and I have connected the 9870 up to this chassis. I am using the example virtual instrument that was recommended from James. I was able to input all of my Read_FIFO and Write_FIFO with my specific ports, and have modified the ports. When I run the FPGA program, it initializes to step 7, and then exits with the following error message: "Too many DMA channels have been requested or some requested are conflicting. The current target has 3 DMA channels." Does anyone have a fix for this? Thanks.

-Daniel Skrabacz

[PaulRB]

Hi Daniel,

The 9074 only has 3 DMA FIFOs, so the error you are seeing is likely caused because you are attempting to use more than three. To get around this limitation, it is recommended that you interleave your data into an array, send the array into the FIFO element by element, and then decimate the array on the receiving end. You can find an example in the Example Finder that will show you how to do this. To open the NI Example, go to Help » Find Examples. Then, in the search tab, type in "DMA." One of the results will be a project called "DMA Buffered Acquisition - cRIO.lvproj." This example shows how to send data from 7 signals through the same FIFO. You will want to implement something similar in your program.

Thanks, 

[dskrabacz]

Hey Paul,

Thank you for getting in touch with me concerning this issue. After doing some more research into my application, I found my problem. I am using Hybrid mode, which dedicates 2 DMA FIFOs of the cRIO to the scan interface mode, and dedicated 1 DMA FIFO to the FPGA mode. My team is building a ground autonomous vehicle, which will receive specific lat/long points from a ground station. My application is this: I am using radios to send TTL data(lat/long points) into the cRIO (I convert the radio data from RS-232 to TTL utilizing outside hardware). What I am going to do, to get around using the FPGA, is to send the radio data straight into NI 9401. This way, I can work off of the Scan Interface. I am still going to use the 9870, for my laser range finder, in this case I will be able to use my single FIFO, just for reading in data. Thanks again for the help.

-Daniel