The names for the subroutines are entered automatically by ascending number, e.g. GR_Subroutine0, GR_Subroutine1... for PLCs with one task. For PLCs supporting two tasks, the names are divided into task numbers:
GR_Task1_ Subroutine1
GR_Task1_ Subroutine2
…
GR_Task2_ Subroutine1
GR_Task2_ Subroutine2
Particularities of GR/GR7 subroutines in comparison to other subroutines
Can be called with FCAL
No internal system variable EN and ENO (to avoid additional temporary Boolean variables and to save program code)
No inputs and outputs allowed (because without ENO variables, correct behavior is not possible)
All edge detection instructions (DF, DFN, DFI...) and timer instructions TM_xxx, F137, F138 are allowed
Direct addresses are allowed
Cannot be called from IEC POUs
The FPWIN GR/FPWIN GR7 programmer is responsible for ensuring that they are not called at the same time because there is no error message if they are called from programs and from interrupts.