Pilz PSS SB FT, Basic license - Manual (Page 114)

6-70 Modular Block System: Burner Management
Standard Function Blocks
Loss of minimum pressure signal as valve VAV1 is incorrectly seated
SB156
If the min-pressure monitor responds within the seal/pressure check the
ENBL output is cancelled.
The
ENBL signal causes an error message in an overriding function: on
the basis of this, the signal SyOK is also reset continuously.
After an acknowledgement reset, i.e. SyOK was set again, the seal/
pressure check can begin again.
Since
SyOK was held at "1" by this test, the ENBL signal will be set
immediately after a program cycle.