Rockwell Automation 1772-LP3 PLC - 2/30 Programmable Controller Programming and Operations Manual - Manual (Page 89)

Introduction to Programming
Chapter 4
4Ć25
WARNING: When the address of a new instruction duplicates
the address of other instructions in the program, the [DATA
INIT] key should not be used without first assessing the
consequences. Pressing the [DATA INIT] key will zero out the
status bits stored at the existing instructions address, which may
interfere with desired machine operation. Damage to equipment
and/or personal injury could result.
NOTE: To determine whether an address has already been used in the
program, the search for specific address function, Section 4.4.3, can be
used to locate user-entered addresses. It will not locate other addresses,
such as those within files or sequencer tables. Therefore, the data table
assignment sheets should be checked to determine whether an address has
been used.
In summary, use the [DATA INIT] key when entering an instruction with
an unused address or when it is desirable to enter new data and clear the
status bits of an already used address.
The [DATA INIT] key should be pressed after the instruction key(s) and
before the address is entered.
OnĆline Programming Procedures
The changes to user program that can be made in the on-line programming
mode include the following:
Insert an instruction
Remove an instruction
Insert a rung
Remove a rung
Change an instruction or instruction address
Correct an error
Programming interruptions
The on-line programming mode is accessible from the industrial terminal
by pressing the key sequence {SEARCH] 52. The processor keyswitch
must be in RUN/PROGRAM position. The heading, ON-LINE
PROGRAMMING, will appear in the top right-hand corner of the screen
highlighted in reverse video.
The procedure for on-line programming in run/program mode is similar
to the procedure for editing in program mode with the exception that the
following three keys have a special purpose in on-line programming: