Hello,
To write and read in the memory bits, you have to address it in the following way ....
modbus plc memory
mw100 = mb100-mb101
memory tcp = 40001
then to write would be m101.0 and by the customer 40001.1
then to write would be m101.1 and on the part of the client 40001.2 and so on.
Test and practice and tell us.
a greeting.