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Multiple Modbus with shared serial port

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Multiple Modbus with shared serial port

I know Lookout lets you do cool things like have multiple serial protocols that share the same hardware serial port.


I have an application where I might like Lookout to simulate a network of Modbus devices for some testing. In this case, I would like to set up multiple Modbus Slave objects, all with different Modbus node addresses and have them all listen on the same serial port. Would this be possible? Each Modbus message received will include the slave number in it. Could several objects listen on the port and only the selected one respond?




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Message 1 of 3
Accepted by topic author MCC_max
08-27-2015 04:09 PM

Re: Multiple Modbus with shared serial port

Yes, lookout modbus slave can work in this way.

But ethernet mode doesn't support it.

Ryan Shi
National Instruments
Message 2 of 3

Re: Multiple Modbus with shared serial port

I am interested in a similar arrangement to the original question - two devices on Modbus RS485.  I have both on a Serial to Ethernet converter, and the Ethernet converter on the same network as my PC.  Each device is set up in Lookout as a Modbus Ethernet device, using the IP address of the converter - differentiated by having a different Identifier matching the Modbus address of each device.  Does this sound like a good set up as far as Lookout is concerned?


The problem that I am having is that only one device responds to the queries sent by Lookout, so my question is part of troubleshooting why its not working.

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