IAI RoboNet Operation Manual page 4

If the positive terminal of the ROBONET's 24-V power supply is grounded, a teaching pendant or PC cannot be connected
directly to the GateWayR unit.
If a teaching pendant or PC is connected directly to the GateWayR unit, the power supply may be short-circuited, causing the
PC or teaching pendant to suffer damage.
This teaching pendant
cannot be used.
PC
24-V power supply
CAUTION
Cannot be connected directly.
GateWay R unit