I/O LEDs¶
Each CPU contains up to 15 LEDs (depending on type) to display the statuses of the inputs and outputs.
| CPU type | LED | Status | Color | LED = ON | LED = OFF | 
PM554 PM564  | 
I0 … I7 (PM554) I0 … I5 (PM564)  | 
Digital input | yellow | Input is ON | Input is OFF | 
| O0 … O5 | Digital output | yellow | Output is ON | Output is OFF | |
| PM564 | AI0, AI1* | Analog input | yellow | Input is ON | Input is OFF | 
| AO | Analog output | yellow | Output is ON | Output is OFF | 
* The analog inputs AI0 and AI1 can be configured as digital input or analog input.