error writing to value.value: Bad_GatewayCommOff how to solve this issue for HR8.1 write

[image] About Communication Modes Video at Inductive University Learn how to change the Designer's communication mode: Comm Off, Comm Read-Only, and Comm Read/Write. The default setting does not allow writing from the Designer to Tag or database sources.

i did the changes as mentioned in the video but still same issue

[image] rsrigokul: Bad_GatewayCommOff This indicates that you are in read-only mode in the designer.

i changed to read/write in the designer. can you please provide the steps if any to cross verify ?

What does the message say now? Perhaps show a screenshot?

[image] rsrigokul: writing to value.value: Bad_GatewayCommOff Error writing to value.value: Bad

[image] rsrigokul: HR8.1 Show us how you have set up your tag. This above is incorrect. Consider the below OPC Address: ns=1,s=[device]1.HR8 this would get you the whole word, you cannot get one bit out of a holding register unless you have a specific type of modbus device. Either use the …

[MB]HR8.0 this was the OPC address in this same format i am able to read the bool data but write bool date to PLC throwing the above error

[image] Address configuration for s7 1200 as OPC device Ignition Based on your earlier error report, the Modbus implementation in Siemens doesn't support the necessary "Masked Write" function code to change bits in holding registers, and doesn't support the coi…

I understand but I wanted to use Mobbus TCP for Modbus TCP simulation attack. is any other way to write bool tag in S71200?

Address configuration for s7 1200 + Modbus TCP

Ignition

David_Stone October 13, 2025, 7:52am 10

Siemens does not support writing to the Holding Registers in this way. I suggest you use the Siemens driver instead.