Panasonic GM1 User Manual page 555

The "ModbusTCP_Slave_Device" object will be added to the "LANPort1" object.
3.
Double-click "ModbusTCP_Slave_Device" in the navigator pane.
The "LANPort1" object will be displayed.
Select the "General" tab and set appropriate values for each item.
Item
Watchdog
Slave port
Unit ID
Holding registers (%IW)
Input registers (%QW)
4.
Select the "Modbus TCP Slave Device I/O Mapping" tab.
You can allocate variables to holding registers and input registers.
WUME-GM1RTXOP-01
Description
If no valid command is received from the master during the preset time period,
the holding register (%IW) will be set to zero.
Settable value: 500 to 200000
Port number used by the slave (local unit)
Settable value: 1 to 65535
A station number is set.
Settable value: 1 to 247
The number of holding registers is set.
Buffer size of holding register: 1 to 4096
The number of input registers is set.
Buffer size of input register: 1 to 4096
13.3 MODBUS
13-29