Siemens Simatic S7 Series System Manual

Program instructions
7.6 Counters
S7-200 SMART
System Manual, 09/2015, A5E03822230-AC
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Change direction in modes 0 and 1
The following steps describe how to configure HSC0 for change direction for single-phase
counter with internal direction (modes 0 and 1):
1. Load SMB37 to write the desired direction:
SMB37 = 16#90
– Enables the counter
– Sets the direction of the HSC to count down
SMB37 = 16#98
– Enables the counter
– Sets the direction of the HSC to count up
2. Execute the HSC instruction to cause the CPU to program HSC0.
Loading a new current value (any mode)
The following steps describe how to change the counter current value of HSC0 (any mode):
1. Load SMB37 to write the desired current value:
SMB37 = 16#C0
– Enables the counter
– Writes the new current value
2. Load SMD38 (double-word-sized value) with the desired current value (load with 0 to
clear it).
3. Execute the HSC instruction to cause the CPU to program HSC0.
Loading a new preset value (any mode)
The following steps describe how to change the preset value of HSC0 (any mode):
1. Load SMB37 to write the desired preset value:
SMB37 = 16#A0
– Enables the counter
– Writes the new preset value
2. Load SMD42 (double-word-sized value) with the desired preset value.
3. Execute the HSC instruction to cause the CPU to program HSC0.

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.