C135 PCS 7 (PCS7)
6C
6 Cielo Ciencia y Tecnología
·Publicada en C135 PCS 7 (PCS7)

Configuring and Testing Feedback Monitoring Fault Alarms on APL MotL Faceplates

Configuring and Testing Feedback Monitoring Fault Alarms on APL MotL Faceplates

To trigger 'Fail to Start' (Feedback Run error) and 'Fail to Stop' alarms on the APL MotL faceplate, feedback monitoring must be enabled (Monitor = 1), and the command must remain unacknowledged by the feedback input longer than the configured dynamic monitoring time (MonTiDynamic). When a start command is issued without FbkRun, the faceplate displays a temporary 'time delay' hourglass while MonTiDynamic counts down; an alarm is only asserted once the timer expires. For single-feedback Direct-On-Line (DOL) motors, FbkClose must be left unconnected or inverted from FbkRun, and message suppression (MsgLock) must be disabled.

Table of Contents

Architecture of APL MotL Feedback Monitoring

In SIMATIC PCS 7 Advanced Process Library (APL), the large motor block MotL (FB 1850) governs motor actuation, interlocking, and health diagnostics.

Supervision of the physical motor contactor relies on two core feedback inputs:
* FbkRun: Digital input reflecting motor running state (e.g., auxiliary contact from the motor starter or run confirmation from a variable frequency drive).
* FbkClose: Digital input reflecting motor stopped/isolated state (utilized primarily in reversing drives, dampers, or specialized circuit breakers).

For standard Direct-On-Line (DOL) motors featuring a single run contact, FbkClose is not physically present. If FbkClose is left unconnected, internal logic evaluates stopped feedback based on FbkRun = 0.

Feedback monitoring is governed by the supervisory input parameter Monitor. If Monitor = 0, feedback tracking is completely bypassed, meaning the block commands outputs without checking whether the motor actually started or stopped, suppressing all monitoring alarms.

Dynamic vs. Static Monitoring and Faceplate Indicators

When testing MotL in simulation or on the test bench, engineers frequently mistake transient runtime indications for faults:
1. Dynamic Monitoring (MonTiDynamic): Defines the time allowed for the motor to transition between states (e.g., from stopped to running). When an operator clicks Start, MotL sets output Start = 1 and begins counting down MonTiDynamic (default: 3 seconds).
* The "Time Delay" Indicator: During this active countdown, the faceplate displays a yellow hourglass or "Delay" status string. This indicates normal travel/startup time. It is not an error.
* The Monitoring Trip: Only if MonTiDynamic expires and FbkRun remains 0 does the block trip:
* Asserts internal fault flag MonDynErr = 1 ("Dynamic feedback error / Fail to start").
* Drops the output command Start = 0 to protect the contactor.
* Generates a high-priority process alarm in the WinCC Alarm Logging banner.
2. Static Monitoring (MonTiStatic): Defines the maximum allowed duration of a feedback dropout while the motor is already in steady-state operation. If FbkRun drops to 0 while commanded running, MonTiStatic counts down before asserting MonStaErr = 1.

Step-by-Step Simulation and Configuration Workflow

To configure and simulate feedback fault indications on the faceplate deterministically:

  1. Verify Monitoring and Timing Parameters in CFC:
    * Open the CFC chart containing MotL.
    * Ensure Monitor = 1 (enable monitoring).
    * Set MonTiDynamic to a testable duration (e.g., 5.0 seconds).
    * Ensure MsgLock = 0 (alarms enabled).
  2. Handle Single Feedback for DOL Motors:
    * If the physical motor has only one run auxiliary contact, leave input FbkClose completely unconnected (do not invert or link to constants unless specifically using two-sensor breakers).
    * Ensure FbkRun is connected to the channel driver block (Pcs7DiIn).
  3. Simulate 'Fail to Start' Fault:
    * Keep FbkRun = 0.
    * On the WinCC faceplate, switch the motor to Manual mode.
    * Click Start.
    * Observe the faceplate status line: it displays the dynamic delay indication for 5.0 seconds.
    * Once the 5.0 seconds elapse, observe that the motor trips: the block state displays the red fault icon, the faceplate shows Feedback error, and an alarm is added to the alarm list.
  4. Simulate 'Fail to Stop' Fault:
    * Set FbkRun = 1 and run the motor.
    * Issue a Stop command on the faceplate while forcing FbkRun = 1 continuously.
    * After MonTiDynamic elapses, the block asserts MonDynErr = 1 and flags a stop failure.

Verification

  • In WinCC Runtime, open the MotL standard faceplate.
  • Check the Preview view of the faceplate. Confirm that Monitoring displays an active check mark.
  • Induce a feedback fault in test mode. Verify that:
  • The motor symbol in the process graphic turns red or flashes error status.
  • The faceplate header displays the red exclamation badge.
  • WinCC Alarm Control logs the message @1%s@ Feedback run error.

Limitations and Operational Precautions

  • In production plants, setting MonTiDynamic too short causes nuisance trips on large motors that require several seconds to spin up and engage auxiliary run contacts.
  • For safety-related drives, feedback monitoring inside MotL is purely operational; it does not replace hardware Emergency Stop circuits or SIL-rated safety relays.
  • If Feature.Bit24 is enabled, local authorization or external trip signals can override dynamic monitoring behavior.

Engineer FAQ

  • Why did the faceplate show 'time delay' instead of an error immediately?
    Industrial motors do not start instantaneously. MotL deliberately waits for the duration of MonTiDynamic before declaring a feedback failure.
  • Why does my motor have no stop indication?
    For a DOL motor, stopping simply de-energizes the contactor (Start = 0). If no dedicated stop sensor is fitted, the faceplate shows normal stopped status (gray) unless a stop feedback timeout occurs.
  • Can I adjust monitoring times from the faceplate?
    Yes. In the MotL Parameter view, authorized operators can adjust MonTiDynamic and MonTiStatic within configured engineering limits.

Technical References

  • SIMATIC PCS 7 Advanced Process Library (APL) Function Manual: MotL Block (A5E43360408-AA).
  • SIMATIC PCS 7 OS Process Control System; Graphic Objects and Faceplates Manual.
  • Siemens Industry Online Support Entry ID 109801081: Configuring Motor Supervision in PCS 7 APL.

Related Articles

Related Tags

PCS 7, APL, MotL, Faceplates, Feedback Monitoring, Alarms, Motors, Troubleshooting

20 respuestas