# Address configuration for s7 1200 + Modbus TCP

**URL:** <https://forum.inductiveautomation.com/t/address-configuration-for-s7-1200-modbus-tcp/111360>\
**Category:** Ignition\
**Tags:** designer\
**Created:** [October 11, 2025, 11:35am UTC](https://forum.inductiveautomation.com/t/address-configuration-for-s7-1200-modbus-tcp/111360 "2025-10-11T11:35:32Z")\
**Posts on this page:** 1\
**Showing post:** 10

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**Author:** ![David\_Stone](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/david_stone/32/79749_2.png) [@David\_Stone](https://forum.inductiveautomation.com/u/David_Stone)\
**Post date:** [October 13, 2025, 7:52am UTC](https://forum.inductiveautomation.com/t/address-configuration-for-s7-1200-modbus-tcp/111360/10 "2025-10-13T07:52:16Z")

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> [@Address configuration for s7 1200 as OPC device](https://forum.inductiveautomation.com/t/address-configuration-for-s7-1200-as-opc-device/96583/24):
>
> 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 coil function codes. So, no can do with Modbus. It should be possible with the native driver using boolean tag syntax as Kevin suggested in [comment #17 above](https://forum.inductiveautomation.com/t/address-configuration-for-s7-1200-as-opc-device/96583/17), as long as you satisfy all of the preconditions for the native driver's use with S7 1200/1500 devices: (An S7+ driver is coming in Ignition v8…

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

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