Question

Greetings!

Problem with RS485 service.

I need to connect ADAM-4017 module with RUT955 by RS485 interface. It is nesessary to setup parameters "Data bits = 8" and "Stop bits = 1" on the RUT955, but there is no such setting. Is it possible to do it and how?

Answer 1

Hello,

RS485 does not have configurable data and stop bits, but by default data bits value is 8 and stop bits is 1.

Comments

Thank you very much, you reassured me.

I tried to use two wires from Ehernet patch cord, connecting "Data +" on ADAM to R_P on RUT955, and "Data -" to R_N (central slots on RUT955). Should this work?

Is it nesessary  to use Ground on RUT955? I read, that its preferable, but should work without it also.

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Hi,

If you are planning to use two wire RS485, better connect Data+ on ADAM to shorted D_P with R_P on RUT955 and Data- to shorted D_N and R_N, same as in picture. This will ensure, that you can send and receive data from one device to other.

Also, more info about wiring RUT955 RS485 can be found in wiki: https://wiki.teltonika.lt/index.php?title=RS232/RS485#2-Wire_and_4-Wire_Networks

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Can you please elaborate on the rationale of dropping Data and Stop bits from RS485 configuration options (according to 2015 manual they used to be there) ?

N.B. Our intention for RUT955 is to use is it for remote Modbus access, so the default setting of 8 Data bits and 1 Stop bit suits the purpose, but I can envisage some other cases where different settings could be required...

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Hi,

It's hardware limited, so there is no way to configure RS485 port to use other than 8 data and 1 stop bit.  However, if you need to use RS485 with different data or stop bit values, try USB tools "USB to serial" option (first you have to install USB tools package from System -> Packages). Here you with RS485 to USB converter you can configure different values, but this function is limited to work on in Over IP mode.