Dear Emil,
the feature in Profibus looks like with what is required for Modbus.
Could you implement the same feature for Modbus too?
"Define in the Slave the area which is accessible by the Master",
and if the Master attempts to Write in this area an error coded reply will be transmitted back.
Although I believe that what is needed is a new SCANEX fb, as Joe Tauser has mentioned in his post,
which seems not so difficult.
I totally agree with Walkerok and Joe comments (+1 , +1 on both guys comments by me too).
Anybody have worked with remote I/O modules or other industrial equipments like Drives, Meters, Indicators etc.
have met the situation of wrong addressing commands.
This feature is provided build even in products costing 45 Euro (panel indicator),
which is about the cost of the extra serial port in the Unitronics PLC, but the PLC is not just a dummy indicator.
PLC is included in the system to perform the control of it.
Leaving a "back door" open, providing access to the control logic can be a disaster.