Siemens SIMATIC S5-100U, System Manual

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S5-100U Function Modules
You can read the current count in the STEP 5 program. The actual value is displayed as a signed
whole number in two's complement and lies in the range - 32,768 to +32,767.
Note
Before you enable the outputs to be switched on by setting the enable input to “1”,
make sure the following conditions exist:
• Both setpoints were transferred.
• The overflow bit=0.
• The SYNC bit=1.
If you ignore these prerequisites, the outputs are switched on directly when the actual
value=0.
The diagnostic bit and the output are reset with the “0” signal at the enable input. Outputs Q 0 and
Q 1 are also reset when the programmable controller goes from RUN to STOP.
The following examples show the switching on of the output at the selected setpoint. There are
three possibilities:
• Reaching the setpoint in the direction of a rising actual value
• Reaching the setpoint in the direction of a falling actual value
• Reaching the setpoint in the direction of a rising actual value, then a reversal of direction and a
reapproaching of the setpoint in the opposite direction
Example 1: Approaching a Setpoint in Up-Count Direction
Figure 15-22. Approaching a Setpoint in Up-Count Direction
Output,
diagnostic bit
setpoint reached
Example of
actual value
Enable input
a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a
Direction of traverse
1000 2000 3000 4000 5000 6000 7000
Setpoint
• Actual value=1000: The enable input is set to “1”.
• Actual value=3000: The setpoint is reached, output and diagnostic bit “setpoint reached” are
set.
• Actual value=6000: The enable input is set to “0”, output and diagnostic bit are reset.
.
EWA 4NEB 812 6120-02b
15-35