I've been looking for the wiring specifics for an RJ45 connection to Modbus and have found very misleading information. I have included a picture which is from Schneider working on the principal that they would know.
Chris, I do not believe that there is any standard for an RJ45 Modbus connection. I have used many RJ45 connectors in the past and I have always had to refer to the equipment vendor's documentation and mostly use conversion from their standard to RS-232 standard 9-pin D-shell connectors. I have used RS-485 signal levels in the past as well, but only with full documentation from the vendor of the converters or devices. Good Luck! Doug Lyons
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The Schneider picture posted by Chris is "3.5.2 Connectors pin-out for optional 4W-MODBUS", Page 30.
This is quite uncommon, but the Pins4/5+8 is also used for the very common "3.5.1 Connectors pin-out for 2W-MODBUS" Page 29.
Edit:
Okay, I now see your sentence "I do not believe that there is any standard for an RJ45 Modbus connection" could also be read like "Surely there is a standard in the papers, but many manufacturers do not care about it". In this case you're probably right.
(I'm not a native English speaker, so I sometimes miss nuances in statements...)
;-)
HTH,
Sarge
Last edit: Sarge (sergeantkolja) 2022-11-19
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Sarge, Thank you very much for your follow-up comment. I find it very informative and hopefully it will help out any others who might come here for this or a similar problem.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Chris, I do not believe that there is any standard for an RJ45 Modbus connection. I have used many RJ45 connectors in the past and I have always had to refer to the equipment vendor's documentation and mostly use conversion from their standard to RS-232 standard 9-pin D-shell connectors. I have used RS-485 signal levels in the past as well, but only with full documentation from the vendor of the converters or devices. Good Luck! Doug Lyons
Ha Doug, believe it or not ... or read the official Doc from modbus.org:
https://modbus.org/docs/Modbus_over_serial_line_V1_02.pdf
;-)
The Schneider picture posted by Chris is "3.5.2 Connectors pin-out for optional 4W-MODBUS", Page 30.
This is quite uncommon, but the Pins4/5+8 is also used for the very common "3.5.1 Connectors pin-out for 2W-MODBUS" Page 29.
Edit:
Okay, I now see your sentence "I do not believe that there is any standard for an RJ45 Modbus connection" could also be read like "Surely there is a standard in the papers, but many manufacturers do not care about it". In this case you're probably right.
(I'm not a native English speaker, so I sometimes miss nuances in statements...)
;-)
HTH,
Sarge
Last edit: Sarge (sergeantkolja) 2022-11-19
Sarge, Thank you very much for your follow-up comment. I find it very informative and hopefully it will help out any others who might come here for this or a similar problem.
Moving to 'closed' now. Thanks.