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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

0 votes
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?
0 votes
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!
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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