8.3.2
Ladder Diagram
This traditional PLC programming language, with its rung-like structure, executes from
top to bottom. The logic execution is thought of as
power flow
, which proceeds down
along the left
rail
of the ladder, and from left to right along each rung in sequence.
MUL_
INT
I1
I2
Q
%I0001
%Q0001
Relay
Power flow into function
Power flow out of function
Coil
%R0124
%R0123
CONST
00002
Multiplication function
Power
Rail
The flow of logical power through each rung is controlled by a set of simple program
functions that work like mechanical relays and output coils. Whether or not a relay passes
logical power flow along the rung depends on the content of a memory location with
which the relay has been associated in the program. For instance, a relay might pass
power flow if its associated memory location contained the value 1. The same relay
would not pass power flow if the memory location contained the value 0.
If a relay or other function in a rung does not pass logical power flow, the rest of that rung
is not executed. Power then flows down along the left rail to the next rung.
Within a rung, there are many complex functions that can be used for operations like
moving data stored in memory, performing math operations, and controlling
communications between the CPU and other devices in the system.
Some program functions, such as the Jump function and Master Control Relay, can be
used to control the execution of the program itself.
Together, this large group of Ladder Diagram relays, coils, and functions is called the
Instruction Set
of the CPU.
106
GFK-1503E
VersaMax PLC User Manual
For public disclosure
Summary of Contents for VersaMax PLC
Page 16: ...Notes 16 GFK 1503E VersaMax PLC User Manual For public disclosure ...
Page 38: ...Notes 38 GFK 1503E VersaMax PLC User Manual For public disclosure ...
Page 50: ...Notes 50 GFK 1503E VersaMax PLC User Manual For public disclosure ...
Page 92: ...Notes 92 GFK 1503E VersaMax PLC User Manual For public disclosure ...
Page 112: ...Notes 112 GFK 1503E VersaMax PLC User Manual For public disclosure ...
Page 224: ...Notes 224 GFK 1503E VersaMax PLC User Manual For public disclosure ...
Page 292: ...Notes 292 GFK 1503E VersaMax PLC User Manual For public disclosure ...
Page 316: ...Notes 316 GFK 1503E VersaMax PLC User Manual For public disclosure ...
Page 317: ......