Siemens Simatic S7 Series System Manual

Program instructions
7.1 Bit logic
S7-200 SMART
154 System Manual, 09/2015, A5E03822230-AC
7.1.4
STL logic stack instructions
STL
1
Description
ALD
The AND Load instruction (ALD) combines the values in the first and second levels of the stack using a logical
AND operation. The result is loaded in the top of stack. After the ALD is executed, the stack depth is decreased
by one.
OLD
The OR Load instruction (OLD) combines the values in the first and second levels of the stack, using a logical
OR operation. The result is loaded in the top of the stack. After the OLD is executed, the stack depth is de-
creased by one.
LPS
The Logic Push instruction (LPS) duplicates the top value on the stack and pushes this value onto the stack.
The bottom of the stack is pushed off and lost.
LRD
The Logic Read instruction (LRD) copies the second stack value to the top of stack. The stack is not pushed or
popped, but the old top-of-stack value is destroyed by the copy.
LPP
The Logic Pop instruction (LPP) pops one value off of the stack. The second stack value becomes the new top
of stack value.
LDS N
The Load Stack instruction (LDS) duplicates the stack bit (N) on the stack and places this value on top of the
stack. The bottom of the stack is pushed off and lost.
AENO
AENO is used in the STL representation of the LAD/FBD box ENO bit. AENO performs a logical AND of the
ENO bit with the top of stack for the same effect as the ENO bit of a LAD/FBD box. The result of the AND op-
eration is the new top of stack.
1
Not applicable for LAD or FBD
LDS (Load Stack) Input
Data type
Operands
N
BYTE
Constant (0 to 31)

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.