Cyclic Counting With Software Start (Ccss) - Siemens SIMATIC S5 IP 281 Equipment Manual

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Cyclic Counting with Software Starl (CCSS)
6.3.5
Method of
When the software gate opens, the counter is loaded with the load value,
operation and begins to count starting with this value.
If a counting range limit is exceeded (overflow or underflow), the counter
is loaded again with the load value, and resumes counting starting with this
value.
The counter is stopped when the software gate closes.
The counter behaves as shown below when the load value corresponds to
a range limit. Example: counting mode 1, 16 bits, positive counting range
Gate control
Software gate
Start:
stop:
Notes
This operating mode cannot be set unless the gate function has been en-
abled by the GEN bit (bit 1 in control register 1/2). Otherwise the IOM mes-
sage ("illegal operating mode") is output and the ERROR LED goes on.
The settings must thus be performed in the sequence listed below.
1. Enable gate function (GEN in control register 1/2)
2. Set operating mode (parameter register 1/2)
Underflow
Example:
Load
Value
0000 (hunter counts
"continuously".
0000 to FFFF+OOOO
Counter stops at
Operating Modes and Functions
Load valua
Direction of Counting
I
FFFFH.
Overflow
I
I
Down
Counter stops at
OrIOOH.
Counter counts
'continuously".
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