S5 AWL Command: UN (AND NOT)
S5 AWL instruction UN (AND NOT): Syntax, S7 equivalent, code examples. Negated AND operation for the VKE.
S5 AWL Command: UN (AND NOT)
The UN instruction performs a logical AND NOT operation. It reads a boolean operand, negates it, and ANDs the result with the current VKE.
Syntax
UN <operand>
S7 Equivalent
| S5 AWL | S7 STL | S7 SCL |
|---|---|---|
UN E 0.2 | AN I 0.2 (EN) / UN E 0.2 (DE) | ... AND NOT NotAus |
Code Example
Emergency stop circuit (active-high, NC contact):
U E 0.0 // Start button
UN E 0.2 // NOT emergency stop (E 0.2 = TRUE means E-Stop pressed)
= A 4.0 // Motor on
A 4.0 is TRUE when E 0.0 is TRUE and E 0.2 is FALSE (emergency stop not pressed).
Common Pattern: Self-Holding Circuit with E-Stop
U E 0.0 // Start
O A 4.0 // Self-hold
UN E 0.2 // E-Stop
= A 4.0 // Motor
Related Commands
- U (AND) — AND without negation
- ON (OR NOT) — OR with negation
Part of the S5 AWL Command Reference. Maintained by PLCcheck.ai.
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