You can read the count value in the feedback interface. The count value is displayed in S7
format.
Function Explanation Note
Set count value The count value is set to 0 when the following
events occur:
● Startup of the CFU
● Count value exceeds the high counting limit
● Restart of the CPU (STOP -> RUN)
● CPU/CFU connection is restored
-
Record and
evaluate pulses
The pulses at the digital input are recorded and
evaluated according to the parameter assign‐
ment.
"Edge selection" parameter:
● On rising edge
● On falling edge
● On rising and falling edge
High counting
limit
The high counting limit is configurable. "High counting limit" parameter: range *:
1 to 4294967295 (2
32
-1)
Reaction to vio‐
lation of the high
counting limit
When the count value violates the high counting
limit, the further behavior of the counter depends
on the configuration.
Parameter "Reaction to violation of the high counting
limit (Page 41)":
● Stop counting
● Continue counting
Stop counting The counter stops at the following events:
● Internal gate closed (SW gate/HW gate)
● CPU in STOP
● CPU/CFU connection is terminated (for
example, PN cable disconnected)
Note:
If the HW gate is to be used, select a free channel of the
CFU at the "Hardware gate channel" parameter.
Load counter A count value can be loaded via the control in‐
terface.
Load count value via control interface (Page 44):
● Control bit (LD_SLOT)
● "Load value" parameter range *: 0 to 4294967295
(2
32
-1)
Comparison val‐
ue
A comparison value can be configured. "Comparison value" parameter; range *:
1 to 4294967295 (2
32
-1)
Show range of
count value
The range in which the current count value is lo‐
cated as compared to the count limits and the
comparison value can be queried via the
STS_DQ status bit (bit in the feedback interface).
The status of STS_DQ depends on the setting of the
"Set output DQ (Page 41)" parameter:
● Between comparison value and high limit
● Between comparison value and low limit
Hardware inter‐
rupt
It is possible to generate a hardware interrupt
when status bit STS_DQ changes from 0 to 1.
"Hardware interrupt" parameter:
● Lock
● Comparison event for DQ occurred
Output compari‐
son event at the
digital output
It is possible to output the STS_DQ status bit di‐
rectly at a digital output of the CFU.
"DQ channel" parameter:
To output the comparison event on a digital output, se‐
lect a free channel of the CFU at the "DQ channel" pa‐
rameter.
* Note on use with PCS 7
The parameter permits values up to 32 bits without sign. The maximum value is FFFF FFFFH (4 294 967 295).
In PCS 7, the representation is limited to 2
31
-1 by the DINT data type.
Operating modes and functions
5.3 Counting
SIMATIC CFU
38 Commissioning Manual, 08/2019, A5E39252870-AD
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