An intermittent overshoot after pause does not, by itself, establish a faulty CTRIO card. The supported diagnostic path is to prove whether the PLC sets the mapped Suspend Output bit while the pause stage is active, whether stage execution prevents that rung from running, and whether motion continues because of mechanical momentum after the output stops.
Separate the three possible mechanisms
| Mechanism | Expected observation | Decision |
|---|---|---|
| Suspend command is not executed | The physical pause input turns on, but the Suspend Output bit does not set. | Trace stage eligibility and ladder execution before replacing hardware. |
| CTRIO does not respond to the command | The Suspend Output bit is confirmed on, but the CTRIO output does not stop. | Confirm the output mapping and test the bit independently of the stage sequence. |
| Mechanical overtravel | The CTRIO output stops, but the machine continues moving. | Investigate inertia and the machine's stopping system rather than treating continued travel as proof of a card fault. |
Confirm the Suspend Output mapping
If the CTRIO output mapping occupies V2030 through V2061, B2056.2 is the Suspend Output bit. Setting B2056.2 on immediately stops the CTRIO output. Because that identification depends on the stated mapping, verify the configured output range before relying on this address.
A missing Suspend command allows the CTRIO to continue running while the rest of the machine remains paused. When pause clears, the motion state may therefore be farther advanced than the stage program expects, producing apparent overshoot or failure to resume normally.
Trace the intermittent stage condition
The pause signal is a physical PLC input, so HMI communication delay is not the primary path in this case. Intermittent behavior instead supports checking whether the stage containing the SET instruction is active on every pause request. A true input cannot execute a rung located in an inactive stage.
- Monitor the physical pause input, B2056.2, and active-stage status together.
- Operate the machine through repeated pause and resume cycles until the failure occurs.
- At the failed cycle, determine whether the pause input turned on and whether the stage containing the B2056.2 SET rung was executing.
- If the input is on but B2056.2 remains off, correct the stage path so every permitted pause condition reaches the suspend logic.
- If B2056.2 turns on, continue with an independent output-response test before suspecting the card.
Test the command independently
Use DirectSOFT Data View to observe B2056.2 during operation. Under controlled and safe machine conditions, manually set the bit and determine whether the CTRIO output stops. This separates ladder sequencing from CTRIO response.
| Pause input | B2056.2 | CTRIO output | Interpretation |
|---|---|---|---|
| On | Off | Running | The suspend rung did not execute, its stage was inactive, or the assumed mapping is incorrect. |
| On | On | Running | Verify mapping and configuration; if both are correct, investigate command response. |
| On | On | Stopped | The command path works; measure whether observed travel occurs after output removal. |
Verify the correction
After changing the stage sequence, repeat pause requests from every operating stage in which pause is allowed. Verify that the physical input turns on, the correct suspend bit sets during the same event, the CTRIO output stops, and the machine resumes from an expected state. If short confirmation signals are being missed, capture their state transitions first; add timers or extra wait stages only when the trace proves that the current stage sequence advances before the required signal sets or clears.
FAQ
Does missing B2056.2 cause CTRIO overshoot after pause?
If outputs are mapped to V2030-V2061, B2056.2 is the Suspend Output bit. If it is not set during pause, the CTRIO can continue running while the machine sequence is paused.
Why does the CTRIO pause fail only sometimes?
The physical pause input may turn on while the stage containing the SET rung is inactive. Monitor the input, B2056.2, and active stage together during the failed cycle.
How do I test whether the CTRIO card is faulty?
First verify the configured output mapping, then monitor and manually set the Suspend Output bit in DirectSOFT Data View under safe conditions. If the output stops, focus on stage logic or mechanical overtravel rather than replacing the card.