485 Send Echo

TurnipTruck

Greetings,

When communicating with RS485 serial devices on Axcent 3 serial ports, the strings sent echo back on the receive even though 485 is enabled via the SET_BAUD command.

This does not occur on Netlinx serial ports when 485 is enabled. Is there something that I am missing to prevent the echo on Axcent 3 ports?

Thanks!

Stephen Bolton

TT,

Does this still occur if you remove the field cabling? (particularly from the device end)

I don't believe I've seen this before and am wondering if there is a wiring issue here perhaps...

Just a thought - you may have done it already!

bmitchell

Not sure about the AXcentIII's, but when I was using RS485 with the AXC-232 cards and the cardframes, I would send the command "EON" to prevent the echo of the characters.

TurnipTruck

Stephen Bolton wrote:

Does this still occur if you remove the field cabling? (particularly from the device end)

The echo occurs because the send and receive pairs at the Axcent 3 are tied together as they have to be for 485. Disconnecting the device end still shows the echo, just not the return data which appears after the echo.

Marc Scheibein

Afaik only NetLinx will do 485 echo filtering, and the AXcess hardware never did.