Trigger Signal Input (Trigger Input)
This is the input that carries on/off information from an external contact into the system. It usually works as a dry contact: when the contact closes, the input terminal is connected to chassis and the command is detected. The blue wire on the GS740-3P is a trigger terminal working with this logic; contact with GND is interpreted as a command.
A dry contact means a switch with no voltage of its own. The system itself supplies the signal voltage; the external element only closes this line to chassis or opens it. The advantage is that no voltage incompatibility problem arises when connecting two systems working at different voltages.
Three points are watched in the connection:
- The chassis reference of the contact and the chassis reference of the controller must be the same point; a voltage difference between different chassis points leads to false triggering.
- Long trigger lines can pick up noise in the engine bay; keep them short or route them separately from power cables.
- An unused trigger terminal is insulated; a terminal left exposed can touch metal with vibration and produce an unexpected command.
The trigger input is not a safety input. No emergency stop input or engine protection input is declared on the GS740 and GS740-3P; these functions must be built with the engine's own protection chain.
Context in which this term is used: Electronic speed and throttle control on diesel engines