Contact Instructions; Standard Contacts; Not; Positive, Negative Transition - Siemens Simatic S7-200 CPU 210 System Manual

5.2

Contact Instructions

Standard Contacts

L
n
A
D
n
/
S
LD
T
A
L
O
LDN
AN
ON

Not

L
A
NOT
D
S
NOT
T
L

Positive, Negative Transition

L
A
P
D
N
S
EU
T
L
ED
You can have a total of 32 transition instructions in a program. These can be any
combination of Positive Transition (EU) and Negative Transition (ED) instructions.
S7-200 Programmable Controller, CPU 210
C79000-G7076-C235-01
The Normally Open contact is closed (on) when the bit value of
address n = 1.
In STL, the normally open contact is represented by the Load,
And, and Or instructions. These instructions Load, AND, or OR
the bit value of address n to the top of the stack.
The Normally Closed contact is closed (on) when the bit value
of address n = 0.
n
In STL, the normally closed contact is represented by the Load
n
Not, And Not, and Or Not instructions. These instructions
n
Load, AND, or OR the logical Not of the bit value of address n to
the top of the stack.
n
n
n
Operands:
These instructions obtain the referenced value from the image
register, which is updated at the beginning of each CPU scan.
The Not contact changes the state of power flow. When power
flow reaches the Not contact, it stops. When power flow does
not reach the Not contact, it sources power flow.
In STL, the Not instruction changes the value on the top of the
stack from 0 to 1, or from 1 to 0.
Operands:
The Positive Transition contact allows power to flow for one
scan for each off-to-on transition. In STL, the Positive Transition
contact is represented by the Edge Up instruction. Upon
detection of a 0-to-1 transition in the value on the top of the
stack, the top of the stack value is set to 1; otherwise, it is set to
0.
The Negative Transition contact allows power to flow for one
scan, for each on-to-off transition. In STL, the Negative
Transition contact is represented by the Edge Down instruction.
Upon detection of a 1-to-0 transition in the value on the top of
the stack, the top of the stack value is set to 1; otherwise, it is
set to 0.
Operands:
n: I, M, SM
none
none
Instruction Set
5-3