RTOR (Retentive Timer On with Reset)
Retentive on-delay timer with integrated reset input for accumulated time clearing.
The RTOR (Retentive Timer On with Reset) is a variant of the retentive on-delay timer that includes an explicit reset input as part of the function block interface. It accumulates time while enabled and retains the value when disabled. The built-in reset input provides a clean, self-contained way to clear accumulated time without requiring a separate reset instruction. RTOR is used in applications where run-time tracking with periodic reset is needed.
Parameters
Inputs
| Name | Type | Description |
|---|---|---|
| IN | BOOL | Timer enable input |
| PT | TIME | Preset time value |
| R | BOOL | Reset input - clears ET and Q |
Outputs
| Name | Type | Description |
|---|---|---|
| Q | BOOL | Timer done output |
| ET | TIME | Accumulated elapsed time |
Ladder Logic Example
// Ladder Logic - RTOR Timer // // |----[ Compressor_On ]----[RTOR Service_Timer]----| // | IN: Compressor_On | // | PT: T#1000h | // | R: Service_Complete | // | Q: Service_Alarm |
Structured Text Example
VAR
Service_Timer : RTOR;
Compressor_On : BOOL;
Service_Alarm : BOOL;
Service_Complete : BOOL;
END_VAR
Service_Timer(IN := Compressor_On, PT := T#1000h, R := Service_Complete);
Service_Alarm := Service_Timer.Q;20 Production-Ready Ladder Logic Templates
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Platform-Specific Implementation
Siemens (TIA Portal)
Use TONR with reset parameter in TIA Portal.
Allen-Bradley (Studio 5000)
Use RTO with RES instruction.
CODESYS
Custom implementation required using persistent variables.
Common Applications
- Compressor service intervals
- Belt replacement tracking
- Bearing lubrication schedules
- Total operating hour logs
Common Mistakes to Avoid
- Confusing RTOR with standard TON behavior
- Not persisting accumulated value across power cycles
Frequently Asked Questions
What is RTOR (Retentive Timer On with Reset) in PLC programming?
Retentive on-delay timer with integrated reset input for accumulated time clearing. The RTOR (Retentive Timer On with Reset) is a variant of the retentive on-delay timer that includes an explicit reset input as part of the function block interface. It accumulates time while enabled and retains the value when disabled.
What are common applications of RTOR (Retentive Timer On with Reset)?
RTOR (Retentive Timer On with Reset) is commonly used for: Compressor service intervals, Belt replacement tracking, Bearing lubrication schedules, Total operating hour logs.
How do I use RTOR (Retentive Timer On with Reset) in different PLC platforms?
Siemens: Use TONR with reset parameter in TIA Portal. Allen-Bradley: Use RTO with RES instruction. CODESYS: Custom implementation required using persistent variables.
Related Function Blocks
RTO (Retentive Timer On)
Timer retains accumulated value when input goes FALSE; requires manual reset.
View Reference →TONR (Timer On-Delay Retentive)
Siemens retentive on-delay timer that accumulates time across multiple enable cycles.
View Reference →TON (Timer On-Delay)
Starts timing on rising edge, output activates after preset delay.
View Reference →TOF (Timer Off-Delay)
Output stays TRUE for preset time after input goes FALSE.
View Reference →TP (Timer Pulse)
Generates a fixed-duration pulse on rising edge of input.
View Reference →Stop Writing Ladder Logic From Scratch
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