The RC7M controller uses fuses for its outputs to prevent damage due to overcurrenting. The fuses typically blow when a particular output is shorted, thus causing a surge of current to run through a specific port. A fuse can also blow if too much power is being pulled through I/O or if a device connected to the controller’s 24V source uses too much current. The RC7M has multiple fuses located in multiple locations inside of the controller.
The fuses that are most prone to failure at located on the mini I/O board. This requires you to remove the top cover of the controller to access these fuses.
Here is an image of the fuses and their locations.
The following chart shows the purpose of each fuse. The polyswitch fuses are resettable fuses. They are reset when the controller is rebooted. All the inputs are fused with polyswitches.
The fuse status can be checked without removing the fuses on the board. Each fuse has 2 small metal pads on top of the fuse which can be used to confirm continuity.
If you remove the fuse you can probe the pins on the bottom. These fuses may also come with a see through body.
You can also reference the attached pdf detailing the fuses inside the RC7M controller.