Ensuring compliance with a keystroke

There are four similar control units on the HLI which can be used to command keypresses.

In this chapter the control units are called HBKeyControlX where the wildcard X can have the following values: (nothing), 2, 3, , 9. In the part ST-path of the following table the names of all present control units are listed.

Handover of GUI requests:

To hand over a keypress request arrived from the GUI to the PLC the enabled control units are scanned in the following order: HBKeyControlUnit_Key, HBKeyControlUnit_Key2, HBKeyControlUnit_Key3, …, HBKeyControlUnit_Key9. The first unit with a request semaphore equal to FALSE is used to hand over the keypress request to the PLC. Therefore the PLC must check all control units with X_Enable set to TRUE if the X_requestSemaphore is set.