Siemens SIMATIC Manual page 77

Operator Control and Monitoring
You can make your operator input in the VAT_LoopControlS variable table.
The controller can be changed to manual at the LMNS_ON switch. After a warm
restart on the CPU, the controller is in manual. If LMNS_ON is set, the outputs
QLMNUP or QLMNDN can be controlled at the inputs LMNUP or LMNDN in
manual mode.
PID Temperature Control
A5E00125039-02
Examples for the Temperature Controllers
6-13