Specifications

SIMATIC Instructions
9-30
S7-200 Programmable Controller System Manual
C79000-G7076-C233-01
Clock 0
1
External
Direction
Control
(1 = Up)
0
1
0
Current value loaded to 0, preset loaded to 4, counting direction set to Up.
Counter enable bit set to enabled.
Counter
Current
Value
PV=CV interrupt generated
1
2
3
4
3
2
1
PV=CV interrupt generated and
Direction Changed interrupt generated
4
5
Figure 9-13 Operation Example of Modes 3, 4, or 5
When you use counting modes 6, 7, or 8 and a rising edge on both the up clock
and down clock inputs occurs within 0.3 microseconds of each other, the
high-speed counter may see these events as happening simultaneously. If this
happens, the current value is unchanged and no change in counting direction is
indicated. As long as the separation between rising edges of the up and down
clock inputs is greater than this time period, the high-speed counter captures each
event separately. In either case, no error is generated and the counter maintains
the correct count value. See Figure 9-14, Figure 9-15, and Figure 9-16.
Count
Up
Clock
0
1
Count
Down
Clock
0
1
0
Current value loaded to 0, preset loaded to 4, initial counting direction set to Up.
Counter enable bit set to enabled.
Counter
Current
Value
PV=CV interrupt generated
1
2
3
4
5
2
1
4
3
PV=CV interrupt generated and
Direction Changed interrupt generated
Figure 9-14 Operation Example of Modes 6, 7, or 8