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S5-95F
4.5.1
Connection of Counter Inputs
Example:
A pulse generator is to be connected to counter A (IW 36).
24 V
Counter B (IW 38) is connected in the same way as counter A.
4.5.2
Parameterizing Counter Inputs in DB1
Parameterizing a counter input means that you specify the following in DB1:
•
Which counter should count
•
Whether a counter should count the positive or negative edge of a pulse
•
Up to which value the counter should count (comparison value)
•
Which signal group a counter should be assigned to.
Make sure when presetting the comparison value that the counter does not trigger OB3 interrupts
too frequently. You should therefore select a comparison value which is not too small; the
recommended value for the period between two OB3 interrupts is approx. 20 ms.
The following applies irrespective of parameterization:
•
The counters only count up
•
The maximum counting frequency is 350 Hz
•
The counter inputs can be used as OB3 interrupt DIs when appropriately shielded.
Parameterization of the Signal Group for Onboard Counters
Note
If you use the onboard counters for safety-related counting tasks, the system reaction for
the selected signal group must be "STOP" or "Passivation". If the system reaction on
faulty onboard counters you select is standard value generation after "AND", "OR" or
"OLD VALUE", you must not use the counter values for safety-related functions after a
counter failure, since the counters at times process single-channel values in the case of
discrepancies.
EWA 4NEB 812 6210-02
Counter B IW 38
Counter A IW 36
M
Figure 4-14. Connecting a Counter Input
Installing and Connecting the Basic System
Subunit A
1
24 V DC
2
3
M
4
5
Subunit B
6
6
7
7
M
8
8
4
9
9
4-19
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