485 Send Echo

TurnipTruck · January 2007

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 · January 2007

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 · January 2007

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 · January 2007

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 · January 2007

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

485 Send Echo

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