Hi radar17892,
all set, the point is that we need somewhere define on which Marker Word to assign. This is done with MU-Modbus RTU acyclic request. If I set all of this parameters I will have on marker area assignment all 32 markers related to selected MW colored with green (Read). If I want to have Read/write is in yellow. To have the writ function must be orange.
When I upload program with this configuration I will have few seconds before Modbus RTU goes in fault. To reset the fault I need to reupload a program or reboot the PLC.
I'm also sniffing the communication between Master and Slave but no data is transferred.