Normally closed contact XIO
Passes power while the tag is off.
Global.StopPBXIO
| Tag | After two scans |
|---|---|
| StopPB | 0 |
How it works
Passes power while its BOOL operand is false; blocks it while the operand is true. The stored tag is not inverted.
How it's used
Use XIO where a rung needs a BOOL to be off: a Stop button, a fault, a full sensor.
Global.StartPBXIC
Global.MotorXIC
Global.StopPBXIO
Global.MotorOTE
| Tag | Value |
|---|---|
| StartPB | 0 |
| StopPB | 1 |
| Motor | 0 |
StopPB was pressed. XIO StopPB stopped passing power and Motor turned off.
Operands
| Operand | Data type | Read or write |
|---|---|---|
| Source | BOOL | Reads |
Common mistakes
- Expecting it to invert the stored valueThe contact changes whether power passes; the tag itself stays unchanged.
Learn it in a lesson
- NOT: the normally closed contactBeginner · 15 min
- Field devices and a fail-safe StopBeginner · 20 min