RS 422 @ 8Mbit/s is it possible with Labview FPGA??

[julesjay]

Hi,

I've to read and write data over an RS422 link at a rate of 8Mbit/s.

Do you think it's possible to implement RS422 @8Mbit/s with labview FPGA?

I know that I will have to make electrical adaptation to use RS422 signals with FPGA card.

Can the FPGA IP available on this website do this?

Thanks a lot

Julesjay

[ChristopheS.]

Hi,

Yes it's possible to implement this into FPGA, if you adapt the electrical signal.

You can found on the link below all information about this :

http://digital.ni.com/public.nsf/allkb/7ADB475DF68DAB518625713A0052799A?OpenDocument

Regards,

[julesjay]

hi,

Thanks for your answer.

So there is no limitation of speed? I've just to run the vi with a 8 MHz clock to do a 8Mbit/s RS422?

[joji1]

Yes it is definately possible.  We did this recently on a project (same 8 Mbit/s) using the 9401 module. For 422, I would use a PXI-78xx series, then use the GeoTest http://pxi4test.com/downloads/pdf/GX5641DS.pdf  GX6541 board to easily translate the IO to 422.  Their board handles up to 35 MHz.

I also tested B&B Electronics 422-to-TTL converter  http://www.bb-elec.com/bb-elec/literature/422TTL_4305ds.pdf and  it didn't do too bad at 10 MHz but had about a 16ns of rise time when I used a 9401 (which has a about a 10 ns rise time). 

[joji1]

Also for the code we just started with the 232 example but then modified with to use a SCL where we could precisely control the rate and delays on the data lines.

Message Edited by joji1 on 05-15-2008 01:14 AM

[dongiulio]

Sorry JoJi1 for reopen this old thread.

I need to implement a custom communication protocol with cRIO with 9401 at 2 Mbps with the output at the electrical level of rs422.

Could you confirm me that there are no problem using the B&B Electronics 422-to-TTL converter?

Thank you,

Giulio Quadrini

[Joji]

Hi Dongiulio,

Yes, the B&B converter worked well past 2Mbps.  I don't have the scope results of my findings, but I tested it up to 10MHz and it was fine for our purposes of less than 10% rise time.