The output registers of a Modbus Master Device Module contain the imported Modbus data for other ION modules to use. The output labels are derived from other registers as shown below:
<label><bit number>@<slave name>[value]

The label is acquired from the Modbus Master Map modules Device Map register (The bit number applies to Packed Boolean formats only).

ION Enterprise has a known issue with the use of @ symbol in OPC registers, which by default exists in the outputs of the Modbus Master Device Module. Hence, these registers cannot be made available for OPC directly from the Modbus Master Device Module. An alternative solution can be the use of a "dummy" arithmetic module in the meter or the VIP.