Rockwell Automation 9323-S5500D A.I. SERIES MICROLOGIX 1000 AND PLC-500 SOFTW - Manual (Page 131)

MicroLogix 1000 and PLC-500 A.I. Series Software Reference
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Changing a Rung
You can edit existing rungs by replacing, deleting, and undeleting instructions and
rungs.
Replace Mode
If you replace a rung, the software places a copy of the rung above the original. When
you press [F9] to accept the modifications, the original rung is discarded and replaced
by the modifications. You can also discard the modifications and restore the original
rung by pressing [Esc] prior to accepting the edits.
If you replace an instruction, the current instruction type becomes the default replace
type. Press [Enter] immediately after selecting replace to modify the address, leaving
the instruction type unchanged. If you replace one instruction with another, and the
two instructions have the same addressing requirements, (e.g., replace XIC with XIO)
the old address will become the new default address.
To replace a rung or instruction:
1. Enter edit mode. (From the top menu bar, select [F3] Edit .)
2. Move to the rung or instruction that you want to replace.
Command Portal keys
for this function:
.ER