Stupid question: I see that there is a 1amp fuse on the OSPi. I assume this protects the the Raspberry Pi board from getting fried by the OSPi board? What happens if there is a short on a Solenoid in the field? Is there any protection on the OSPi board if that happens?
The 1amp PTC fuse in conjunction with 5.6V zener diode protects the 5V line. There is no fuse to protect short solenoid on the current version of OSPi. If there is a short on the solenoid, usually what happens is that the voltage from the 24VAC transformer will drop instantly which will result in a reset of the system and hence release the solenoid. In the worst case (say if the transformer’s voltage does not drop even in the event of shorting) the traic of the corresponding solenoid will probably be fried and hence you cannot use that station anymore.