Queries received by the device must be for data items within the defined (and enabled) valid address ranges. Otherwise the station returns an exception response. In addition, server Modbus proxy points under the device must be configured to fall within these address ranges, or else they will have a fault status.

Figure 21.   Modbus Register Range Tables of Modbus server device

You can see these range components under the device when expanded in the Nav tree, as well as in the device’s property sheet.

By default, as copied from the modbusSlave or modbusTcpSlave palette, a Modbus server device has a single Default-named Register Range Entry in each valid range container, with each having an enabled range of from 1 to 64, for Valid Coils Range. The same default applies to the Valid Holding Registers Range, and so on.