Siemens Simatic S7 Series System Manual

Program instructions
7.13 Program control
S7-200 SMART
304 System Manual, 09/2015, A5E03822230-AC
LAD
FBD
STL
Description
LSCR S_bit
The
SCR
instruction loads the SCR and logic stacks with the value of the
S bit referenced by the instruction.
The resulting value of the SCR stack either energizes or de-energizes the
SCR stack. The value of the SCR stack is copied to the top of the logic
stack so that LAD boxes or output coils can be tied directly to the left
power rail and no preceding contact instruction is required.
The
SCRT
instruction identifies the SCR bit to be enabled (the next S_bit
to be set). When power flows to the coil or FBD box, the CPU turns on the
referenced S_bit and turns off the S_bit of the LSCR instruction (that ena-
bled this SCR segment).
The
CSCRE
(conditional SCR end) instruction, for STL and FBD, termi-
nates execution of the SCR segment when enabled. For LAD, a condi-
tional contact placed before a
SCRE
coil performs the conditional SCR
end function.
The
SCRE
(unconditional SCR end) instruction, for STL and FBD, termi-
nates execution of the SCR segment. For LAD, an SCRE coil connected
directly to the power rail performs the unconditional SCR end function.
SCRT S_bit
CSCRE
SCRE
Input / output
Data type
Operand
S_bit
BOOL
S

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.