Try to reset the controller's E:0821 Short circuit fault by pressing the 'reset' button. If the fault does not clear (even shortly) after pressing the reset button, check if there is an electic leakage with the metal cover. If the fault does clear after pressing the reset button, check the incoming power supply voltage. If the power supply is different than the requested (24±15%), E:0821 will also be triggered.
- Remove both AI and DI connectors to see if the short circuit error disappears after pressing the reset button. If the fault goes away, identify if it is caused by the AI or the DI.
- Remove AI connector, keep DI connector. Does the short circuit error disappear?
- Remove DI connector, keep AI connector. Does the short circuit error disappear?
- After you identify if it's DI or AI, measure the voltage on each input with a multimeter. To identify the short circuit. You can find some examples below:
- Analog input 3: measure between X03 C-ANA3 and GND. (=5V or 24V)
- Analog input 1: measure between X03 C-ANA1 and GND (=24V)
- Digital input: measure between X02 C-DI and GND (=24V)
- Take a look at the display of the controller. If the delivery/sump/temperature (or any other AI) reading is missing, it can indicate that one of the AI's has a short circuit.
- The common (C-XXXX) is the pin who supplies voltage. So always measure between the common pin and GND.
The controller is broken if error E:0821 does not clear after considering the above steps.