Basic Operation - Panasonic FP-M Hardware Manual

5-1. Operating Principles of the Programmable Controller

2. Basic Operation

The basic operation of the programmable controller is:
- To read data from all the input field devices
- To execute the program according to the logic programmed
- To turn the output field devices ON or OFF
The process of reading inputs, executing the program, and updating the outputs is cyclicly repeated in the same
manner.
Programmable Controller
Input
Input
interface
field device
Programmable Controller
X0
R0
Cyclicly
repeated
process
76
Memory for
operands
(for input)
X0
X1
X2
Program Memory for
read
operands
R0
X0 X1
write
R0 R1
read
Y0 Y1
Y0
write
Programmable Controller
Memory for
operands Output
(for output) interface
Y0
Y1
Y2
1 1 Input update stage
The programmable controller reads
information (ON or OFF) at the input
interface and stores it in the memory for
operands.
2 2 Program execution stage
The CPU of the programmable
controller executes the program
according to the logic programmed
....
by reading and writing the
....
information to and from the
....
memory for operands.
The memory for operands is
successively updated according to
the execution of the program.
3 3 Output update stage
Output
field device
~
After program execution, the
information (ON or OFF) in the
memory for operands is written to
the output interface and turns the
output field devices ON or OFF.