Siemens Simatic S7 Series System Manual

Program instructions
7.6 Counters
S7-200 SMART
System Manual, 09/2015, A5E03822230-AC
217
Input / output
Data type
Operand
Cxxx
WORD
Constant (C0 to C255)
CU, CD (LAD) BOOL Power flow
CU, CD (FBD)
BOOL
I, Q, V, M, SM, S, T, C, L, Logic flow
R (LAD)
BOOL
Power Flow
R (FBD)
BOOL
I, Q, V, M, SM, S, T, C, L, Logic flow
LD (LAD)
BOOL
Power Flow
LD (FBD)
BOOL
I, Q, V, M, SM, S, T, C, L, Logic flow
PV
INT
IW, QW, VW, MW, SMW, SW, LW, T, C, AC, AIW, *VD, *LD, *AC, Constant
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
c
ounter 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
Counter bit
Power cycle / first scan
CTU
• CU increments the current value.
• Current value continues to incre-
ment until it reaches 32,767.
The counter bit is set ON when:
Current value >= Preset
• Counter bit is OFF.
• Current value can be retained
1
CTD
• CD decrements the current value
until the current value reaches 0.
The counter bit is set ON when:
Current value = 0
• Counter bit is OFF.
• Current value can be retained
1
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.
The counter bit is set ON when:
Current value >= Preset
• Counter bit is OFF.
• Current value can be retained
1
1
You can select the current value for the counter to be retentive, but not the counter bit value.

Siemens Simatic S7 Series Specifications

General

CPU	Varies by model (e.g., S7-300, S7-400, S7-1200, S7-1500)
Communication Interfaces	PROFIBUS, PROFINET, Ethernet, MPI
Programming	TIA Portal, STEP 7
Programming Languages	LAD, FBD, STL, SCL, GRAPH
I/O Modules	Digital, Analog, Specialty modules available
Operating Temperature	0°C to 60°C (standard models)
Mounting	DIN rail mounting
Operating Voltage	24V DC or 120/230V AC (varies by model)
Protection Class	IP20 (standard models)
Memory	Varies depending on the S7 model. Includes work memory (RAM) for program execution, load memory (EEPROM or Flash) for program storage, and system memory for operating system functions. Memory sizes range from kilobytes to megabytes.