Siemens SIMATIC S7-200 System Manual page 135

Examples of HSC Modes
The timing diagrams in Figure 6-22 through Figure 6-26 show how each counter functions
according to mode.
1
Clock 0
1
Internal
0
Direction
Control
(1 = Up)
Counter
Current
Value
0
Figure 6-22 Operation Example of Modes 0, 1, or 2
1
Clock
0
External
1
Direction
0
Control
(1 = Up)
Counter
Current
Value
0
Figure 6-23 Operation Example of Modes 3, 4, or 5
Current value loaded to 0, preset loaded to 4, counting direction set to up.
Counter enable bit set to enabled.
PV=CV interrupt generated
Direction changed within interrupt routine
4
3
2
1
Current value loaded to 0, preset loaded to 4, counting direction set to up.
Counter enable bit set to enabled.
PV=CV interrupt generated
4
3
2
1
S7-200 Instruction Set
3
2
1
0
- -1
PV=CV interrupt generated and
Direction Changed interrupt generated
5
4
3
2
1
Chapter 6
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