Rockwell Automation 1747-PT1, D1747NP002 Hand-Held Terminal - Manual (Page 216)

Chapter 15
Instruction Set Overview
15–2
Timer and Counter Instructions – Chapter 17
Instruction Name
and Mnemonic
5/02
Only
•
Function – Output Instructions
Timer On-Delay TON Counts time intervals when conditions preceding it in
the rung are true. Produces an output when
accumulated value (count) reaches preset value.
Resets when rung is false (non–retentive).
Timer Off-Delay TOF Counts time intervals when conditions preceding it in
the rung are false. Produces an output when
accumulated value (count) reaches preset value.
Resets when rung is true (non–retentive).
Retentive Timer RTO This is an On-Delay timer that retains its accumulated
value when:
– rung conditions go false;
– the mode changes to program from run or test;
– the processor loses power;
– a fault occurs.
Count Up CTU Counts up for each false–to–true transition of conditions
preceding it in the rung. Produces an output when
accumulated value (count) reaches preset value.
Count Down CTD Counts down for each false–to–true transition of
conditions preceding it in the rung. Produces an output
when accumulated value (count) reaches preset value.
High–speed
Counter HSC Applies to 24 VDC fixed I/O controllers only. Counts
high–speed pulses from a high–speed input. Maximum
pulse rate of 8kHz.
Reset RES Used with timers and counters. When conditions
preceding it in the rung are true, the RES instruction
resets the accumulated value and control bits of the
timer or counter. It is also used to reset position value
and control bits of a sequencer.