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MODBUS IP Communications


Flex727

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  • MVP 2023

When using VisiLogic, I monitor and display system operands SB 143-150 and SDW 14-21 to know that communications are proceeding as expected. Is there any equivalent in UniLogic? How can I know that MODBUS IP communications are working properly (i.e. connected and exchanging data)?

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  • MVP 2023

Thanks! Got it working well. Is there a plan to allow updating the IP address for a MODBUS IP slave PLC through ladder or operator interaction? In other words, if IT makes a change to the IP addressing, I want the customer to be able to make the update without me having to provide a program update (something easily done in VisiLogic).

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  • MVP 2023

Is there a plan to allow updating the IP address for a MODBUS IP slave PLC through ladder or operator interaction? In other words, if IT makes a change to the IP addressing, I want the customer to be able to make the update without me having to provide a program update (something easily done in VisiLogic).

 

Bumping this in the hope of getting an answer to my second question. Currently the IP address of a UniStream PLC can be changed by an operator, but if the PLC is addressing a MODBUS Slave, and the Slave's address is changed, the address the Master is using to communicate with the slave cannot be changed except by the programmer. Is there a plan to improve this?

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Currently the only way to modify the slaves IP address to use the advanced Modbus function blocks, and is not available within the basic Modbus configuration. These settings are not enabled by default but can be added by navigating to the Project menu, selecting Options, then enabling the check box for the Modbus advanced ladder functions. There is also an example project available. Please send an email to support@unitronics.com and we would be happy to send it to you.

 

This requires the ladder to manually connect using the TCP/IP connect block, and then build a struct of information for the Modbus commands. This would allow the IP address of the slave device to be dynamically changed.

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