This looks like as mention J1939 or EOL. With CAN/J1939 dry contacts won’t work other than the fact that it will appear as a “bus off” error causing comms to “fail” on every device connected to it. If it’s only the generator this may not be a bad thing. All serial protocols (Modbus, CAN, LON) are jammed by a dead short.
It could be EOL. In this case the alarm panel is looking for a certain resistance (voltage drop). A “short” indicates alarm. An open indicates broken wire. This is a common fire alarm wiring scheme with smoke detectors but I haven’t seen it in gensets.
I highly doubt it is using NC contacts like an E-Stop because of the resistor.
Paul, Good points..
I have seen Some HMI controllers on generators Dief, Deep sea, Comap uses resistance switching for alarm, Signals. This all depends on the controller programing and series of controller, that is in the unit. Or ground switching with a set of dry contact for a low coolant sensor or oil temp sensor.
I am now curious on what type of controller for the Can-buss operation this unit has. I might have the wiring diagram on file.
I would need the following.
Motor make, and engine number. if possible. Not needed. Lets me know any open can-buss channels if any.
Manufacture of the package unit.
HMI controller manufacture model number.