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KAS Holding Registers Modbus Issue

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For Modbus Slave configuration, once I set a Base Address for a data block of Holding Registers, I cannot change the base address (Invalid Address error). Furthermore, once a Base Address is set for one data block of holding registers, in my example addresses 792 to 811, I can't add another data block of holding registers any lower than the base address I set for my first data block Holding registers (i.e. 792). In my case, I added a data block with addresses 792 to 811, but realized I have another data block I want to add starting address 732, but I cannot add a new data block unless it is equal or greater to 792. I was able to add a data block at address 800 even though that already existed, and a data block at address 9000, but nothing before 792 once this first data block was set. Deleting the Slave Configuration, or recompiling and re-downloading does not fix this, the only way is to start a new project.

Can anyone else reproduce this? I would really like to be able to change/add data blocks if I need to without having to keep starting a new project each time. I will try a workaround by adding a data  block at 0, so anything after I can add (hopefully) without issue.




I think I found the answer to this question. For those that may also come across this, you can right-click on the Data Block and select MODBUS Slave addresses and set the First valid for Holding register back to 1.

Eric Futak - Tue, 10/29/2019 - 12:42
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