Siemens SIMATIC S5-100U, System Manual

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Function Modules S5-100U
Disabling the Counter
A negative edge at the enable input disables the counter. The outputs, diagnostic bits, and the
counter are not reset. You can continue reading the current count. A positive edge at the enable
input resets the outputs and the diagnostic bytes.
Reaching the Setpoints - Setting the Outputs - Resetting the Outputs
If setpoints have been preselected and the counter is enabled, the module counts the positive edges
at the counter input. The count is incremented by “1” with every leading edge.
After setpoint 1 has been reached, output Q 0 is enabled. At the same time, status bit S1 is set.
After setpoint 2 has been reached, output Q 1 is enabled. At the same time, status bit S2 is set.
As long as the enable input is active, the counter counts the pulses. After the enable command has
been cancelled, the counter is disabled. The actual value remains constant.
You can read the current count in the STEP 5 program. The actual value is displayed as an
unsigned whole number and must be between 0 and 65,535.
Note
If no setpoint is preselected, the respective value “0” is assigned. The corresponding
output is enabled with the positive edge of the enable input.
Example: Setpoints S1=2 and S2=4 are entered into the counter
Counter status
Counting pulses
Enable
input
Output Q 1
(setpoint 2
reached)
0 1 3 2 4 5 5 0 1 2
a a a a
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Pulse is not counted because
counter is disabled by enable
input=0.
The count is "frozen" to the
current value.
Output Q 0
(setpoint 1
reached)
Figure 15-16. Switching the Outputs Dependent on the Status of the Counter and
the Enable Input
When the programmable controller goes from RUN to STOP, outputs Q 0 and Q 1 are reset.
15-28
EWA 4NEB 812 6120-02b