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RS485 2 wires on Digi one IAP

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The RS485 port 1 work perfectly well using 4 wires cabling. Unfortunately, our Modbus slave uses RS485 2 wires only. What is the configuration or the cabling to use a 2 wires RS485 on port 1 instead of a 4 wires RS485?
asked Jul 29, 2015 in Modbus and Industrial Automation by Jacques Stevens New to the Community (0 points)

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3 Answers

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Port 1 is the screw terminal. Keep in mind that we tie the rxd/txd +/- pins together when the device is in two wire mode.
You can use 3, or 6 for the + signal. And 4, or 7 for -. We also recommend that you use pin 5 gnd.
answered Jul 30, 2015 by Wingmaster1800 New to the Community (37 points)
Thank you very much for your answer! For the cabling, no problem of course. But I did not see any command to put the IAP in 2 wires mode in the configuration wizard. Is there a special command to use with telnet or tying the pins together is enough?
commented Jul 31, 2015 by Jacques Stevens New to the Community (0 points)
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RS485 is enabled using the dip switch for the serial port. I have included a link to the quickstart guide which show the different modes used by the Digi One IAP.

http://ftp1.digi.com/support/documentation/90000634_E.pdf
answered Jul 31, 2015 by Wingmaster1800 New to the Community (37 points)
Thank you very much, it works now!
commented Aug 10, 2015 by Jacques Stevens New to the Community (0 points)
0 votes
It'd be really cool if this were documented in a manual somewhere. Maybe include some example wiring diagrams like the rest of the industrial controls world?
answered Dec 21, 2018 by baj New to the Community (1 point)
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