ISA-88 Batch Control Skill

Key rules:

• A Process Cell must contain at least one Unit.
• A Unit operates on only one batch at a time (in batch processing).
• Equipment Modules may be recipe-aware (directly initiated by recipes) or generic.
• Control Modules are the interface to physical equipment (sensors, valves, motors).

2. Process Model

The process model describes what needs to happen, independent of equipment. It is the basis for general and site recipe procedures.

Process
  Process Stage         (major independent part of a process)
    Process Operation   (major processing activity, e.g., react, charge)
      Process Action    (minor processing activity, e.g., add catalyst, heat)

Fuuz mapping: The process model maps conceptually to how work orders and production flows define the sequence of manufacturing steps. A Fuuz work order's operations list aligns with process operations; individual steps within those operations align with process actions.

3. Procedural Control Model

The procedural control model describes how equipment executes the process. It is the basis for master and control recipe procedures.

Procedure                 (entire batch, runs across process cell)
  Unit Procedure          (contiguous production in a single unit)
    Operation             (major processing sequence in one unit)
      Phase               (lowest procedural element, e.g., "Add Material")

Relationship between models:

Process Model          Procedural Model         Physical Model
-----------            ----------------         --------------
Process           -->  Procedure           -->  Process Cell
Process Stage     -->  Unit Procedure      -->  Unit
Process Operation -->  Operation           -->  (within Unit)
Process Action    -->  Phase               -->  Equipment Module

4. Recipe Types

ISA-88 defines four recipe types, progressing from abstract to executable:

Recipe contents (all types):

• Header -- identification, version, approval status
• Formula -- process inputs (materials), process parameters (temp, time), process outputs (expected yield)
• Equipment Requirements -- constraints on allowable equipment
• Procedure -- ordered steps (structure depends on recipe type)
• Other Information -- regulatory, safety, packaging info

Key principles:

• General/Site recipes use the Process Model structure (equipment-independent).
• Master/Control recipes use the Procedural Control Model structure (equipment-dependent).
• A control recipe is created from a master recipe for each batch, then may be modified during execution.
• Master and control recipes are mandatory; general and site may be omitted.

5. PackML State Machine

The PackML state machine (ISA-TR88.00.02-2022) defines a standard set of states and transitions for automated machines and units. This is the primary reference for Fuuz workcenter state management.

5.1 The 17 States

Critical distinction:

• Holding/Held = internal machine issue (operator refills, internal fault). Triggered by Hold command.
• Suspending/Suspended = external line issue (upstream starved, downstream blocked). Triggered by Suspend command.

5.2 State Transition Diagram (Simplified)

                            [Abort from any state] --> ABORTING --> ABORTED
                                                                      |
                                                                   [Clear]
                                                                      v
    STOPPED <--[SC]-- STOPPING <--[Stop from most states]         CLEARING
       |                                                             |
    [Reset]                                                       [SC]
       v                                                             v
    RESETTING --[SC]--> IDLE                                     STOPPED
                          |
                       [Start]
                          v
                       STARTING --[SC]--> EXECUTE --[Complete]--> COMPLETING --[SC]--> COMPLETE
                                            |   ^                                        |
                                         [Hold] |                                     [Reset]
                                            v   |                                        v
                                         HOLDING [Unhold]                             RESETTING
                                            |     ^
                                         [SC]     |
                                            v     |
                                           HELD --+

                                          EXECUTE
                                            |   ^
                                      [Suspend] |
                                            v   |
                                       SUSPENDING [Unsuspend]
                                            |       ^
                                         [SC]       |
                                            v       |
                                        SUSPENDED --+
                                            |
                                       [Unsuspend]
                                            v
                                      UNSUSPENDING --[SC]--> EXECUTE

SC = State Complete (acting state finishes its procedure)

5.3 State Commands

5.4 Unit/Machine Modes

Modes define which subset of states, commands, and transitions are active:

Mode behavior:

• Each mode uses a subset of the base state model (states can be disabled per mode).
• The same state name may have different logic in different modes (e.g., Execute in Production = making product; Execute in Manual = jogging).
• Mode transitions may be restricted (e.g., cannot go from Production to Manual while in Execute).

5.5 Mapping PackML to Fuuz Workcenter States

When implementing workcenter state management in Fuuz:

OEE time classification by state:

• Producing: Execute
• Planned Downtime: Stopped (scheduled), Idle (waiting for schedule)
• Unplanned Downtime: Held, Suspended, Aborted, Stopping, Aborting
• Changeover: Resetting, Starting, Completing (depends on context)

6. ISA-88 / ISA-95 Integration

ISA-88 and ISA-95 are complementary. ISA-95 defines the enterprise-to-control-system information exchange; ISA-88 defines the control-system-level execution of batch processes.

Equipment Model Alignment

Activity Model Alignment

Key Integration Points

• Recipes to Work Orders: ISA-95 production schedules become ISA-88 batch schedules. In Fuuz, work orders (ISA-95 segment) carry recipe parameters (ISA-88 formula) to the workcenter.
• State Reporting Upward: ISA-88 state transitions at the unit/process cell level feed ISA-95 production performance data. In Fuuz, workcenter state history feeds OEE and production dashboards.
• Resource Management: ISA-95 manages resources at the work center level; ISA-88 manages allocation/arbitration within the process cell. In Fuuz, equipment availability and material tracking span both concerns.

7. Cross-References

• isa-95 -- Enterprise-control integration framework. Equipment hierarchy levels 0-4, functional model, information exchange categories. Use ISA-95 for enterprise-level context and ISA-88 for control-level detail.
• fuuz-industrial-ops -- Workcenter state management implementation, alarm evaluation, OEE time classification, UNS topic structure. The practical Fuuz patterns that implement ISA-88/PackML concepts.
• fuuz-schema -- Batch-oriented data model design. Use ISA-88 physical model to guide equipment hierarchy design; use recipe model to guide product/BOM/routing schemas.
• fuuz-flows -- Batch process automation flows. Use ISA-88 procedural control model and PackML state machine to design state transition flows, recipe execution flows, and production tracking flows.