1 Publication 1747-RM001G-EN-P - November 2008
Chapter
2
Basic Instructions
This chapter contains general information about the basic instructions and
explains how they function in your application program. Each of the basic
instructions includes information on:
• the instruction symbol.
• the instruction format.
• the instruction usage.
The Basic Instructions detailed in this chapter are listed in Table 2.1.
Table 2.1 Basic Instructions
Instruction
Mnemonic
Instruction Name Purpose Page
XIC Examine if Closed Examines a bit for an On condition. 2-3
XIO Examine if Open Examines a bit for an Off condition. 2-3
OTE Output Energize Turns a bit On or Off. 2-4
OTL and OTU
Output Latch and
Output Unlatch
OTL turns a bit on when the rung is executed, and this bit retains its
state when the rung is not executed or a power cycle occurs. OTU
turns a bit off when the rung is executed, and this bit retains its
state when the rung is not executed or when power cycle occurs.
2-4
OSR One-shot Rising Triggers a one-time event. 2-5
TON Timer On-delay Counts timebase intervals when the instruction is true. 2-9
TOF Timer Off-delay Counts timebase intervals when the instruction is false. 2-10
RTO Retentive Timer Counts timebase intervals when the instruction is true and retains
the accumulated value when the instruction goes false or when
power cycle occurs.
2-11
CTU Count Up Increments the accumulated value at each false-to-true transition
and retains the accumulated value when the instruction goes false
or when power cycle occurs.
2-13
CTD Count Down Decrements the accumulated value at each false-to-true transition
and retains the accumulated value when the instruction goes false
or when power cycle occurs.
2-14
HSC High-speed Counter Counts high-speed pulses from a fixed controller high-speed input. 2-15
RES Reset Resets the accumulated value and status bits of a timer or counter.
Do not use with TOF timers.
2-20
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