Releasing Blocked Units and Completing Archived Batches in SIMATIC BATCH

In SIMATIC BATCH, when a batch is aborted or stopped, closed, and archived but its physical unit remains locked—preventing subsequent automated batches from acquiring the unit—the unit must be released through manual administrative intervention. Because an archived batch is read-only in the runtime database, an operator with appropriate security rights must either force-release the unit allocation from the Unit Allocation overview in Batch Control Center (BatchCC) or temporarily restore the batch from the archive to reset its operational state and clear lingering unit locks.

Batch Lifecycle States and Unit Allocation Locks

SIMATIC BATCH strictly enforces recipe execution rules according to the ISA-88 batch standard. When a batch recipe executes, it dynamically requests, allocates, and releases technological process units (e.g., Mixers, Reactors, Holding Tanks) through procedural recipe phases.

Under abnormal operating conditions:
* Premature Termination (Stopped / Aborted): If an operator stops or aborts a running batch while recipe phases are actively occupying physical equipment, the normal phase deallocation sequence is bypassed.
* Archival Locking: If the operator subsequently executes Close and Archive on the batch without first terminating active phase allocations, the batch record transitions into an immutable, read-only state within the Batch database.
* Unit Blocking: The runtime database retains the internal flag Unit Allocated to Batch [ID]. When subsequent automated batches attempt to acquire the unit, the SIMATIC BATCH allocation manager blocks the transition, leaving incoming batches stalled in queue awaiting equipment availability.

Step-by-Step Procedure to Force Release Units and Clear Batches

Follow this procedure in SIMATIC BATCH Control Center (BatchCC) to release blocked equipment and restore automatic scheduling.

Prerequisites

Access to SIMATIC BATCH Control Center (BatchCC) on the BATCH Server or an authorized client.
User account logged in with permissions for Force unit release / Force allocation in SIMATIC Logon / BATCH User Administration.

Method 1: Force Unit Deallocation in BatchCC (Immediate Release)

Open Batch Control Center (BatchCC).
In the navigation tree, locate and expand Plant Data or open the Unit Overview / Allocation Overview window.
Locate the blocked process unit (e.g., Reactor_01) displaying status Allocated or showing an unexpected lock icon.
Right-click the blocked unit and inspect the context menu:
* Select Unit Allocation -> Release Unit (or Force Deallocation).
A confirmation dialog appears warning that the unit is being forced out of its active assignment. Enter an electronic signature / comment if SIMATIC Logon audit tracking is enabled.
Confirm the release. The unit status transitions immediately to Idle / Available, allowing queued batches to acquire the equipment.

Method 2: Restoring and Formally Terminating an Archived Batch

If the batch record itself must be modified to establish a clean completed status:
1. In BatchCC, expand Orders -> Batches.
2. Select the Archived filter or open the Archive Management dialog.
3. Locate the affected batch (status Stopped + Closed + Archived).
4. Right-click the batch and select Restore Batch from Archive.
5. The batch record shifts back into the active database.
6. Open the restored batch in the recipe monitor:
* Right-click the batch header and select Set to Completed (or Terminate Batch).
* Ensure all residual recipe phases display status Completed or Terminated.
7. Once all equipment is confirmed released, execute Close Batch followed by Archive Batch.

Verification

In BatchCC, verify that the unit displays a green or neutral icon indicating state Free / Available.
Schedule a new test batch requiring that unit; confirm that the BATCH allocation manager smoothly assigns the unit without stalling at the unit allocation step.
In the BatchCC message log, confirm the event entry: Unit [Unit_Name] released successfully.
Verify on the WinCC OS faceplate that the unit status indicator reflects Free and displays no residual batch IDs.

Limitations and Operational Precautions

Physical Plant Verification: Prior to forcing a unit release, the operator must physically verify that the field equipment (agitators, heating valves, transfer pumps) has been safely shut down and that vessels are clean or properly vented.
Audit Trail Accountability: Force-releasing units generates an audit log entry in the BATCH journal and WinCC Audit database. Always document the operating rationale.
Concurrent Recipe Collisions: Forcing a unit release while an AS controller is still executing residual phase logic can cause severe operational conflicts. Verify that the AS SFC/BMASTER block has fully transitioned to IDLE or STOPPED.

Engineer FAQ

Why did the batch stop other batches if it was already closed?
Closing and archiving a batch saves the historical data record but does not automatically clear active equipment reservations if phases were aborted prematurely.
Can a unit be released directly from WinCC without BatchCC?
If configured on the WinCC Unit Faceplate (@PG_UNIT.pdl), an authorized operator can click the Release Unit button on the OS, which forwards the command to the BATCH server.
What happens to the historical report when a batch is restored?
Restoring a batch allows status updates. When re-archived, SIMATIC BATCH generates an updated, timestamped electronic batch record (EBR) reflecting the administrative termination.
Why is the "Release Unit" option grayed out in BatchCC?
This indicates that the logged-in Windows user lacks the administrative privilege Force Unit Allocation / Deallocation in SIMATIC BATCH User Management.
How do I prevent this from recurring during unplanned plant stops?
Ensure recipes include standard abort/stop logic branches (SOP / EOP) that automatically command active phases to release equipment allocations upon abnormal stoppage.

Technical References

Siemens Industry Online Support Entry ID 109801081: SIMATIC BATCH Operating and Configuration Manual.
Siemens System Documentation: ISA-88 Batch Control Principles and Unit Allocation.
Siemens SIMATIC BATCH Administrator Guide: Electronic Batch Records and Archive Management.