Visual kv series – KEYENCE Visual KV Series User Manual
Page 240
4.3 Setting and Operation of High-speed Counters
3-216
Visual KV
Series
4
Chapter 4 High-speed Counters
4.3.6
Differences with the CTH Instruction between the
Conventional and Visual KV Series
The Visual KV Series has some different high-speed counter operations from the
conventional KV Series [KV-10/16/24/80R(W)/T(W)].
Input-enable relay
•
With the conventional KV Series, the current value of the high-speed counter is
reset when the CTH instruction is executed while the input-enable relay is OFF.
However, the counter continues counting until the end of the scan time. As a
result, when the input-enable relay starts counting again, the counter may al-
ready be incremented by the length of the scan time.
•
With the Visual KV Series, the current value of the high-speed counter is reset at
the falling edge of the input-enable relay, so that the counter does not continue
counting.
High-speed counter (CTH)
•
The conventional KV Series includes high-speed counter CTH0, which is an 8-bit
counter. The period of the internal clock is different from that in the new KV
Series.
•
The Visual KV Series allows you to reset a high-speed counter with external
inputs. Its high-speed counter CTH0 is a 16-bit counter (can also be used as 24-
bit counter).
•
With the Visual KV Series, when using the high-speed counter, the input time
constant must be set shorter by using the HSP instruction or by turning ON
special utility relay 2813.
Phase differential input
The Visual KV Series allows phase differential input for the high-speed counter.
Response frequency
The Visual KV Series provides a response frequency of 30 kHz.
High-speed counter comparator
•
The high-speed counter comparator turns ON the contact when its preset value
matches the current value of the high-speed counter. Consequently, the contact
may turn ON during the scan time.
Be careful when using the contact for one comparator in several points in a
program.
Special utility relay
A portion of the special utility relay assignment is different from that of the conven-
tional KV Series.
0001
CTH0
0004
Count input
Input-enable relay
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