I
OVERVIEW
1
I
Chapter
1
:
Overview of the AIS
PLC
I
IWhat
is
the
AIS
?
I
The Mitsubishi
AIS
programmable logic controller represents a low cost, high
performance, compact micro modular PLC capable of solving almost all types of
industrial control applications from simple relay replacement,
to system control and
networking.
lHow
Does
It
Work
?
I
Similar
to
most PLCs available, the
AIS
operates by executing a sequential control
program (sequence program) starting from the beginning of the program and
finishing at the
'END
instruction contained within the sequence program.
Depending on the results from each individual program section, the central
processing unit (CPU module) will update the conditions of the inputs and outputs.
The timing of the update depends upon the processing method that the CPU
module is set to (dip switch setting), either refresh or direct mode. With the refresh
mode the inputs and outputs are updated at the end of the program, and with the
direct mode the inputs and outputs are updated as and when they are used within
the sequence program. The sequence program itself is stored in
a
random access
memory (RAM) within the CPU module which is battery backed to prevent program
loss due to power failure to the PLC.
A1S
PLC
System
I
Limit
switches
Relay contacts
Key
switches
Push buttons
Thumbwheel
switches
Photoelectric
switches
Input
~
Digital displays
Indicator lamps
Contactors
Electronic valves
Warning alarm
other
electronic
devices
Modules
Analog signals
Encoder
pulses
Servo
amplifiers
Programmer
I
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I
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220 VAC Soflware
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2
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