Enable Operation, For Cpu 103 And Higher - Siemens SIMATIC S5-100U System Manual

S5-100U
8.2.2

Enable Operation, for CPU 103 and Higher

You can use the enable operation (FR) to execute the following operations even without an edge
change.
• Start a timer
• Set a counter
• Count up and down
Table 8-11 presents the enable operation. An example follows the table.
Operation Operand
FR
ID
T
C
Example
Input I 0.0 starts a timer T 2 as an
extended pulse (pulse width 50 s).
This timer sets output Q 1.0 for the
duration of the pulse.
.
.
.
.
If output Q 1.1 is reset repeatedly, the
timer should also be restarted
repeatedly.
EWA 4NEB 812 6120-02b
Table 8-11. Enable Operation
Enable a Timer/Counter
Timers and counters are enabled on the leading edge of the RLO.
This operation restarts a timer, sets a counter, or causes a counter
to count up or down when the RLO "1" is pending at the "Start"
operation.
Parameter
0 to 127
0 to 127
STL
A
L
SE
A
=
A
FR
BE
Meaning
Explanation
I 0.0
KT 500.1
Start a timer T 2 as an extended
T 2
pulse.
T 2
Output Q 1.0 is set for 50 s.
Q 1.0
.
.
.
.
If output Q 1.1 is set (positive
Q 1.1
edge change of the RLO) during
T 2
the time in which input I 0.0 is
set, timer T 2 is restarted. Output
Q 1.0 therefore remains set at the
restarted time or is reset.
If input I 0.0 is not set during the
edge change of output Q 1.1, the
timer is not restarted.
STEP 5 Operations
8-41