Use Of The Associated System Constant - Siemens SINUMERIK MC Commissioning Manual

Note
Hardware interrupts: Response for NCK events
You must issue an attach command before an event occurs from the part program (by
executing a command to output a fast help function). If you do not issue an attach command,
then the NCU is brought into state "Wait for HiFu acknowledgment".
You must reset the NCU in order to exit state "Wait for HiFu acknowledgment".
Result
The properties of the NCK process alarm events have been specified and may have been
assigned to a process alarm OB. The event is also listed in the properties of the selected
hardware interrupt OB under "Start events". A corresponding system constant was added.
Note
Message: "Wait: AuxF acknowledgment missing"
If NCK events, auxiliary functions or NCK hardware interrupts are called without a hardware
interrupt OB being assigned or before one is assigned, the channel message "Wait: AuxF
acknowledgment missing" is issued.
You can only leave this state if you trigger a "power-on reset" of the MCU.
For the NCK signals to be processed in the PLC basic program, you must call
LBP_NCKProcessIRT [FC3] in the hardware interrupt OB (e.g. hardware interrupt [OB40]) next.
5.4.7.5

Use of the associated system constant

When you define the event for NCK hardware interrupts, a system constant is automatically
added whose name corresponds to the associated event name. You can use the system
constant to query in the PLC user program whether a hardware interrupt was triggered and by
which module.
You can find the system constant in the "PLC variables" editor in the "System constants" tab.
MCU commissioning: NC, PLC, Drive
Commissioning Manual, 02/2020, A5E47437618B AB
PLC commissioning
5.4 Creating a PLC program
93