Rockwell Automation 1772-LP3 PLC - 2/30 Programmable Controller Programming and Operations Manual - Manual (Page 12)

Introduction
Chapter 1
1Ć2
With a user-written program and appropriate I/O modules, the PLC-2/30
programmable controller can be used to control many types of industrial
applications such as:
Process control
Material handling
Palletizing
Measurement and gauging
Pollution control and monitoring
The 1772-LP3 processor has a read/write CMOS memory that stores user
program instructions, numeric values and I/O device status. The user
program is a set of instructions in a particular order that describes the
operations to be performed and the operating conditions. It is entered into
memory, rung by rung, in a ladder diagram and functional block display
format from the keyboard of a 1770-T3 or 1784–T50 terminal. The ladder
diagram symbols closely resemble the relay symbols used in hardwired
relay control systems. The functional block displays are an easy method of
programming and monitoring advanced instructions.
During program operation, the PLC-2/30 processor continuously monitors
the status of input devices and, based on user program instructions,
either energizes or de–energizes output devices. Because the memory is
programmable, the user program can be readily changed if required by the
application.
The PLC-2/30 processor’s functions include:
Relay-type functions (Examine On, Examine Off, Output Energize,
Output Latch, Output Unlatch and Branching)
Complete forced I/O
Data
transfer
Data comparison
Three-digit, four-function arithmetic (+, –,
×
, :–) :–:–
Timing functions: On-Delay and Off-Delay, Retentive and Nonretentive
with time bases of 1.0, 0.1 and 0.01 seconds (timing range 0.02 to 999
seconds).
Bidirectional counting (up or down) with a range of 0 to 999 counts.
Self-monitoring/diagnostic
capabilities
Expandable data table
Memory capacity of 16,256 words
896 I/O device capacity is available in local or remote configurations.
896 inputs and 896 outputs when used with specific configurations.
Memory write protect
Program control instructions
- Jump
- Subroutines