Panasonic GM1 Series Reference Manual page 52

5.1 Wiring the Power Supply
● Conversely, depending on your environment, grounding may cause a problem.
As for the GM1 Controller (RTEX-compatible / EtherCAT-compatible), since its power
supply line is connected to the function earth through a high-voltage capacitor, it is no
problem.
● Do not ground the function earth when grounding a plus (+) terminal of the power.
When grounding a plus terminal of the power supply, prepare a power supply dedicated
to the GM1 and do not ground the plus terminal of the GM1 power supply. In some
personal computers, the SG terminal of the internal circuit and shielding are connected.
Furthermore, since the power supply circuit for the GM1 is not isolated, if the plus
terminal of the power supply is grounded, the power supply will be short circuited to
cause a breakdown.
5-4 WUME-GM1H-02