Siemens Simatic S7 Series System Manual page 217

Input / output Data type
Cxxx WORD
CU, CD (LAD) BOOL
CU, CD (FBD) BOOL
R (LAD) BOOL
R (FBD) BOOL
LD (LAD) BOOL
LD (FBD) BOOL
PV INT
Note
Since there is one current value for each counter, do not assign the same counter number to
more than one counter. (Up Counters, Up/Down Counters, and Down counters with the
same number access the same current value.)
When you reset a counter using the Reset instruction, the counter bit is reset and the
counter current value is set to zero. Use the counter number to reference both the current
value and the counter bit of that counter.
See also Configuring the retentive ranges - system block configuration
Counter operation
Type Operation
CTU
CU increments the current value.
•
Current value continues to incre-
•
ment until it reaches 32,767.
CTD
CD decrements the current value
•
until the current value reaches 0.
CTUD
CU increments the current value.
•
CD decrements the current value.
•
Current value continues to incre-
•
ment or decrement until the coun-
ter is reset.
You can select the current value for the counter to be retentive, but not the counter bit value.
1
S7-200 SMART
System Manual, 09/2015, A5E03822230-AC
Operand
Constant (C0 to C255)
Power flow
I, Q, V, M, SM, S, T, C, L, Logic flow
Power Flow
I, Q, V, M, SM, S, T, C, L, Logic flow
Power Flow
I, Q, V, M, SM, S, T, C, L, Logic flow
IW, QW, VW, MW, SMW, SW, LW, T, C, AC, AIW, *VD, *LD, *AC, Constant
Counter bit
The counter bit is set ON when:
Current value >= Preset
The counter bit is set ON when:
Current value = 0
The counter bit is set ON when:
Current value >= Preset
Program instructions
Power cycle / first scan
Counter bit is OFF.
•
Current value can be retained
•
Counter bit is OFF.
•
Current value can be retained
•
Counter bit is OFF.
•
Current value can be retained
•
7.6 Counters
1
1
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