Modbus device tries to read Input registers when none are mapped?

I have a Modbus device. Set up to use only holding registers. It feels logs with

E [d.M.ReadInputRegistersRequest ] [16:22:31]: Received response with ExceptionCode: 0x02 (IllegalDataAddress). device-name=Test Scanner

Ignition-DP-WILLIAM-12_thread_dump20200824-112706.txt (170.6 KB) Ignition-DP-WILLIAM-12_thread_dump20200824-112712.txt (170.6 KB)

Any other OPC UA clients connected to the server? Any other devices configured? Did you at one point have input registers addressed but now you don’t? system.opc.readValue calls? Transaction groups with OPC items?

I did have some IRs mapped. But, I deleted and re-added the device connection. Then I deleted it and totally renamed it. I’ve restarted OPC UA module as well. With no address mapping at all.

No other tags or tgroups. Its pretty fresh install on dev server. No other device connections.

I don’t know how, its holding on to old mapping if that is the case.

But, i am more wondering if Ignition driver would be compatible with a device configured like this. In “holding register only mode”

Its the only way to get the device to put its read data into HRs. That way i can read them as string. Unless you can read strings in IR like you can with HRs


There isn’t an equivalent string read function with IRs. Correct?


A mapping doesn’t influence what data the driver reads at all, only what it shows when you go to browse it.

Disable the device, restart the gateway, enable the device. If it starts reading input registers you definitely have something configured or connected to read from the device.

HRS and IRS should both be valid designations for reading a string from HR or IR tables.