Machine Expert - Basic M221 Modbus RTU write coils

[11thchair]

I am trying to use a TM221CE40R to communicate through the serial port using Modbus RTU. I have a Waveshare USB to RS485 device going to my computer. I set up the Write_Var to multiple words and it works fine. I try to set up the Write_Var to bits and monitor the addressed coils and I get nothing. Figure I don't understand what all the fields mean - thinking the index is not correct. My guess was 40 means %M40.

[11thchair]

Found a solution last night. A YouTube video in Portuguese. ( I know some French and a tad of Spanish). The index was my issue. an index of 40 would refer to %MW40 then look for %MW40:x0 for the coil.