Siemens SIMATIC S5-100U, System Manual

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Function Modules S5100U
15.6.5 Entering New Setpoints for the Counter and Position Decoder
Entering new setpoints is always possible via the PIQ. However, a setpoint is only valid if the
respective output is not switched on. The status of the outputs is displayed with diagnostic bits S1
and S2.
Diagnostic bit S1 (bit 1 in the diagnostic byte)=1: setpoint 1 is reached and output 1 is switched
on.
Diagnostic bit S2 (bit 2 in the diagnostic byte)=1: setpoint 2 is reached and output 2 is switched
on.
Table 15-5. Reaction of the Counter Module during Transfer of the Setpoints
Diag. Bit
S1 = 0
S2 = 0
S1 = 1
S2 = 1
New setpoint 1 is transferred and is valid immediately.
New setpoint 2 is transferred and is valid immediately.
New setpoint 1 only becomes active if a positive edge has appeared at the
enable input.
New setpoint 2 only becomes active if a positive edge has appeared at the
enable input.
Response
Example:
You want to control a drive by using the outputs of the counter module. After a run of positioning,
both setpoints are reached and both outputs are turned on. You can enter the new setpoints by
using the following sequence:
Figure 15-25. Requirement for New Setpoints
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Enable input
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Output Q 0/
Diag. bit S 1
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Output Q 1/
Diag. bit S 2
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S 2
new
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S 1
old
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S 1
new
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S 2
old
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Transfer the new setpoints to the module. Since both diagnostic bits S1 and S2 are set to “1”,
the actual values are not yet accepted.
Switch the signal now at the enable input to “0”. With the falling edge, the outputs are switched
off and the diagnostic bits are reset.
Switch the signal at the enable input again to “1”. The new setpoints are accepted and are
now active.
After reaching the new setpoints, the respective output is switched on again.
15-38
EWA 4NEB 812 6120-02b