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Maximum PLC ID for Modbus RTU
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Topic: Maximum PLC ID for Modbus RTU (Read 12500 times)
ccdubs
Full Member
Posts: 116
Maximum PLC ID for Modbus RTU
«
on:
August 01, 2014, 04:42:34 PM »
I remember reading before that the PLC ID's were only valid up to a limit when using MODBUS RTU. I can't find this reference anymore, could you please confirm what this?
Thanks
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support
Global Moderator
Hero Member
Posts: 3174
Re:Maximum PLC ID for Modbus RTU
«
Reply #1 on:
August 01, 2014, 11:57:49 PM »
According to Modbus specifications the ID for a Modbus slave may only be between 1 and 247.
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Email: support@triplc.com
Tel: 1-877-TRI-PLCS
EDGAR
Jr. Member
Posts: 60
Automating concepts around the world!
Re:Maximum PLC ID for Modbus RTU
«
Reply #2 on:
August 02, 2014, 08:00:25 AM »
Hi, and agreed!
You might be able to handle that many devices. However, if you are using RS-485 network, the RS-485 transceivers may not be capable of driving that many devices in the same network. See
http://www.modbus.org/
also see
http://en.wikipedia.org/wiki/RS-485
for bias network termination and other details.
Ed
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Maximum PLC ID for Modbus RTU