What the GT25-J71E71-100 is
The Mitsubishi GT25-J71E71-100 is an Ethernet communication unit built for the GT25 series of graphic operation terminals, and it sits in the PLC expansion module category so the integrator treats it as an HMI-side network option rather than a backplane I/O slice.
Where it lands on the panel
In a GT25 build this unit gives the terminal its industrial Ethernet link to upstream controllers and peer devices, so the HMI can participate in the same network the PLCs and drives are already speaking on without bolting on a third-party gateway.
Sizing note
The unit ships as a communication-only add-on, so panel-side decisions come down to slot compatibility with the host GT25 terminal and the network protocol stack, not from a current or power rating on the module itself.