I’m having a bit of a bizarre issue currently where if I attempt to configure a modbus device with modbus TCP utilizing an ethernet cable, all of the tag qualities change between unknown and the normal value and the device itself seems to begin malfunctioning, with the display screen on it showing all values as NULL. I’m not sure if this might have to do with the settings that I currently have configured or something of that sort or the device itself?
First thing would be to disable the use of writing ,multiples, as some devices do not have the full Modbus instruction set implemented. If that doesn’t fix it, be sure to turn them back on as they potentially save a LOT of overhead.
Also keep in mind that some low-end devices might only allow one “user” of Modbus TCP at a time, or a small number at a time.