Pilz PSS SB FT, Basic license - Manual (Page 126)

6-82 Modular Block System: Burner Management
Standard Function Blocks SB157
Spurious signals
A third attempt cannot be triggered i.e. no RDY pulses
are created as the internal timer (M064.19=0) has
timed out.
The set
STEP and ENBL outputs from SB152 have no
effect on the SyOK input.
SB157 is in the base state and waits for the first
ignition failure.
After the monitoring time has elapsed, no further re-ignition
is triggered. By pressing the reset button and then the
START button the sequence starts with a defined starting
step (step 1).