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IGEPv2 RS485 problem

posted in IGEPv2
Saturday, May 02 2015, 05:00 PM

I have an IGEPv2 rev. C board. I'm trying to test the RS485 on J940, UART1, but I'm facing a little, I hope, problem.

The test setup is as follow: IGEPv2 connected to a MOXA UPort 1150 RS485/USB converter, connected to a Win7 PC with TeraTerm running (but the same behaviour can be seen with puttytel).

The problem is that I can transmit from the Windows PC to the IGEPv2, but not the other way around.

I added board.ei485=yes to /boot/igep.ini, then I tried with the sample rs485 test program from http://labs.isee.biz/index.php/How_to_use_RS485 without being able to receive anything on the Windows PC.

Then I tried using microcom on the IGEPv2, and do some simple exchange between the PC and the IGEPv2 board, and as I said before, typing on the Windows PC results in data being received by microcom, but not the other way around.

Do you have any idea on what could the problem be ?

Thank you very much indeed,


PS: I'm using the default linux installation on the IGEPv2, uname -a gives "Linux igep00x0 2.6.37 #1 Mon Jun 10 18:25:45 CEST 2013 armv7l GNU/Linux" and dmesg gives "[ 0.000000] Linux version 2.6.37 (maintainer@titan.isee.biz) (gcc version 4.6.4 20120303 (prerelease) (GCC) ) #1 Mon Jun 10 18:25:45 CEST 2013"
Responses (2)
  • Accepted Answer

    Wednesday, May 06 2015, 01:58 PM - #permalink
    Hi fmarini,

    can you try and probe Tx and Rx signals on pins of the U940 IC located under the J940 connector while comunicating between the devices?

    The pins are arranged as follows:

    Rx1o 8
    2 7
    3 6
    Tx4 5


    Alejandro Benete
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  • Accepted Answer

    Wednesday, June 03 2015, 01:58 PM - #permalink
    I tried the example program 485-example.c (http://labs.isee.biz/index.php/How_to_use_RS485) and I worked fine.

    Later I used a microcom in the igepv2 and putty in my pc and works fine.

    You have first tried the 485-example program ? or microcom?

    I think it's important the execution order. First execute the program to configure the rs485 parameters.

    PS:I used an USB-COM485-PLUS1


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