LED Status Display
The LEDs are located at the front of module. There are 2 different groups:
- The 4 system LEDs (PWR,     CS31, S-ERR and I/O-Bus) show the operation status of the module and display     possible errors.
 
- The 26 process LEDs (UP,     inputs, outputs, CH-ERR2 to CH-ERR4) show the process supply voltage and     the statuses of the inputs and outputs and display possible errors.
 
Status of the 4 System-LEDs:
| LED | 
Status | 
Color | 
OFF | 
ON | 
Flashing | 
| PWR/RUN | 
System voltage | 
green | 
Process supply voltage missing | 
Internal supply voltage OK, module ready for communication     with IO Controller | 
Start-up / preparing communication | 
| CS31 | 
CS31 communication | 
green | 
No communication at the CS31 bus module | 
Communication at the CS31 bus OK | 
Diagnosis mode | 
| S-ERR | 
Sum Error | 
red | 
No error | 
Internal error | 
– | 
| I/O-Bus | 
Communication via the I/O-Bus | 
green | 
No expansion modules connected or communication error | 
Expansion modules connected and operational | 
— | 
Status of the 27 process LEDs:
| LED | 
Status | 
Color | 
OFF | 
ON | 
Flashing | 
| DI0 to DI7 | 
Digital input | 
yellow | 
Input is OFF | 
Input is ON (the input voltage is even displayed if the     supply voltage is OFF) | 
– | 
| DC8 to DC15 | 
Digital input/output | 
yellow | 
Input/output is OFF | 
Input/output is ON (the input voltage is even displayed     if the supply voltage is OFF) | 
– | 
| AI0 to AI3 | 
Analog input | 
yellow | 
Input is OFF | 
Input is ON (brightness depends on the value of the analog     signal) | 
– | 
| AO0 to AO1 | 
Analog output | 
yellow | 
Output is OFF | 
Output is ON (brightness depends on the value of the     analog signal) | 
– | 
| UP | 
Process supply voltage 24 V DC via terminal | 
green | 
Process supply voltage is missing | 
Process supply voltage OK | 
– | 
| CH-ERR2 | 
Channel Error, error messages in groups (digital inputs/outputs     combined into the groups 1, 2, 3, 4) | 
red | 
No error or process supply voltage is missing | 
Serious error within the corresponding group | 
Serious error within the corresponding group (e.g. short-circuit     at an output) | 
| CH-ERR3 | 
red | 
| CH-ERR4 | 
red | 
| CH-ERR *) | 
Module Error | 
red | 
– | 
Internal error | 
– | 
| *) All of the LEDs CH-ERR2 to CH-ERR4 light up together |