Feature request: ability to set unit id on a request by request basis

[wz2b]

I have a gateway with multiple "slave" (we should rename that "unit") devices attache. Need to be able to specify slave addr per call, rather than changing the per connection SlaveID which works but raises potential concurrency problems.

[shantanoo]

Just thinking out loud, would setting handler.rtuPackager.SlaveId / handler.SlaveId just before the operation help? https://github.com/grid-x/modbus/blob/master/rtuclient.go has SetSlave function.

[xxandev]

i made it so for myself, maybe it will help
https://github.com/alpr777/modbus
https://github.com/alpr777/modbus/blob/main/example/main.go

[pxnky]

Just thinking out loud, would setting handler.rtuPackager.SlaveId / handler.SlaveId just before the operation help? https://github.com/grid-x/modbus/blob/master/rtuclient.go has SetSlave function.

Then you have to keep the handler around through all the rest of the code. This seems like a very basic feature, I don't understand why the assumption (seems to be) that you only set it once.