Help me about Modbus RTU Communication

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hungqsbk01
Posts: 5
Joined: Fri Aug 08, 2014 10:04 am

Help me about Modbus RTU Communication

Post by hungqsbk01 »

Anyone can give me any idea in this situation.
My HMI works as Modbus Master in Modbus Network. It communicates with 10 Slaves (PLCs). But now it can only read/write from/to the Slave that has the same address to default station. I configured default station in controller setting is 1, and my HMI can only read/write from/to with the controller that has address is 1.
Thanks in advance.
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jcjelektro
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Re: Help me about Modbus RTU Communication

Post by jcjelektro »

use more controller drivers, than station's on one.
modbus.png
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Emil Gundersen
JCJelektro.dk

Dehne
Posts: 1
Joined: Wed Apr 29, 2015 6:02 am

Re: Help me about Modbus RTU Communication

Post by Dehne »

Just to complete this issue.
I had a problem with Modbus RTU using several Modbus Master Drivers. One for each Slave. It gave me communication errors.
Together with the Beijer support we found the solution to add just one Modbus RTU Master driver. To address the slaves, you add the slave station number before the register number in the Controller-column in the Tag-list.

So in the Modbus Master column in the tag list.
To access Register 40001 from slavestation number 2, it would be "2:40001".
To access Register 40001 from slavestation number 3, it would be "3:40001".

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