Pilz PSS SB FT, Basic license - Manual (Page 168)

8-4
Examples
Modular Block System: Burner Management
Example which takes into account different SB enables when
programming:
L M 77.00 .ENBL pilot flame
U M 77.01 .ENBL main flame
= M 90.01 .FLAs flame monitoring.
L M 72.00 .ENBL pre-purge
U M 73.00 .ENBL tightness control
= M 74.00 .Global enable
LN M 74.00 .Global enable
U M 73.01 .Auxiliary flag negative edge ENBL
=N M 73.02 .Pulse flag group enable
R M 73.01 .Auxiliary flag negative edge ENBL
L M 74.00 .Global enable
S M 73.01 .Auxiliary flag negative edge ENBL
L(
L M
75.00 .STOP signal
O M 73.02 .Pulse flag global enable
)
U M
85.00 .Limiter 1
U M 85.01 .Limiter 2
U M 71.00 .ENBL SB154
U M 85.31 .Limiter n
= M90.00 .CHAI safety sequence
Because of this block the safety sequence will not be interrupted as a
result of a
STOP, because the STOP signal is still present if the pulse
of the global enable is detected.
To establish a safety sequence, a cycle must be first run through once.
So the cycle can run through the safety sequence without interruption,
the safety sequence will be inactive for the duration of the cycle.
For this reason the flags M113.03 and M113.04 (permanently specified)
must be supplied to the AND-operation before the global input
CHAI of
SB152 as shown in the diagram on the next page.
5
4
3
2
1
6