How to Implement LPML (OMAC PackML) in SIMOTION D435 Projects

To begin programming an OMAC PackML application using the Siemens LPML (Library PackML) V3.0 library on a SIMOTION D435 controller, install the standard SIMATIC/SIMOTION OMAC PackML V3 Machine and Unit States application example from the Siemens Industry Online Support (SIOS) portal (Entry ID: 49970441). This application example provides pre-configured execution state models, Unit/Equipment module structures, and standardized interface structures that map directly to the ISA-TR88.00.02 (PackML) standard.

Technical Cause: Why Custom State Machine Architectures Fail

Complex motion control equipment, such as multi-axis laser cutting machines, requires synchronized operational states across coordinated drives, safety systems, and process equipment. Attempting to build a custom state machine using basic ladder or structured text logic often results in unhandled state transitions, race conditions between motion tasks and process interlocks, and non-standardized operator interface (HMI) data structures.

The LPML library resolves these issues by implementing the ISA-TR88.00.02 standard directly within the SIMOTION execution environment. It encapsulates the standardized state model—comprising Acting States (such as STARTING, EXECUTE, STOPPING) and Wait States (such as HELD, SUSPENDED, COMPLETE)—into standardized library blocks. This guarantees that process commands (e.g., Start, Stop, Hold, Reset) follow deterministic transition paths and present uniform command/status interfaces to supervisory HMI/SCADA systems.

Plaintext

+-----------------------------------+
               |              STOPPED              |
               +-----------------------------------+
                                 |
                                 | Reset
                                 v
               +-----------------------------------+
               |               IDLE                |
               +-----------------------------------+
                                 |
                                 | Start
                                 v
   +---------------------------------------------------------------+
   |                            EXECUTE                            |
   |  (Laser motion path execution & process parameter control)   |
   +---------------------------------------------------------------+
         |                                           |
         | Hold                                      | Suspend
         v                                           v
+-----------------+                         +-----------------+
|      HELD       |                         |    SUSPENDED    |
+-----------------+                         +-----------------+

Prerequisites

Before integrating the LPML V3.0 library into a SIMOTION motion control project, ensure the following hardware, software, and access requirements are met:

Engineering Environment: Siemens SCOUT or SCOUT TIA with SIMOTION Kernel support matching the target hardware release.
Target Hardware: SIMOTION D435 (Control Unit for multi-axis motion control).
Library Package: LPML_V3 library and the SIMATIC/SIMOTION OMAC PackML V3 Machine and Unit States application package (SIOS Entry ID: 49970441).
Fieldbus & Drive Configuration: Configured SINAMICS S120 drive objects and integrated axes assigned to the SIMOTION execution system.

Implementation Workflow for LPML V3.0 in SIMOTION

Integrating LPML into a SIMOTION D435 project follows a structured sequence: importing the library, configuring the unit state machine, linking physical motion axes, and mapping command interfaces.

Procedure

Import the LPML Library Package:
Download SIOS Entry ID 49970441. Extract the library files and open SCOUT. Import the LPML_V3 library into your project tree under the Libraries folder.
Instantiate the Unit State Machine:
Call the core PackML unit control block (such as LPMLv3_UnitModule) inside a periodic background or synchronous execution task (e.g., BackgroundTaskId or MotionTaskId).
Define Process Modes:
Configure the required PackML modes (e.g., Production, Maintenance, Manual) within the unit module initialization structure.
Map Motion Axes to Execution States:
Link the SIMOTION technology objects (TOs) representing the laser cutting head and positioning axes to the corresponding PackML state handlers:
- In STARTING / RESETTING: Execute home position checks, axis enable routines (_enableAxis), and drive power-up checks.
- In EXECUTE: Call the primary motion routines (e.g., path interpolation, CNC/G-code execution, or multi-axis interpolation).
- In HOLDING / STOPPING: Trigger controlled motion deceleration ramps (_stopAxis or path interrupt commands) and disable process signals (e.g., laser emission).
  5. Connect Command & Status Structures:
  Map physical pushbuttons, supervisory network control tags, or HMI command words to the input control interface structure of the PackML block.

Core Library Architecture and Function Blocks

The LPML library relies on standardized interface structures to process control requests and report unit status.

Control ElementInterface TypeFunctional RoleCommand InterfaceStructure (stCmd)Receives incoming state transition requests (Start, Stop, Hold, Reset, Abort) from HMI or master control.Status InterfaceStructure (stStatus)Outputs current state information, active state duration, mode confirmation, and warning/fault flags.Mode SelectionInteger TagDictates operational mode (1 = Production, 2 = Maintenance, 3 = Manual/Setup).State Machine EngineFunction BlockEnforces ISA-TR88 transitions, preventing invalid operations (e.g., direct transition from STOPPED to EXECUTE without passing through RESETTING and IDLE).

Verification

The LPML implementation is successful when the following criteria are satisfied:

Deterministic State Transitions:
Issuing a Start command while in the IDLE state correctly moves the status interface through STARTING to EXECUTE.
Safe Fault Processing:
Triggering a protective interlock or safety signal in EXECUTE immediately forces the state engine into ABORTING, executes safe stopping routines, and holds the system in ABORTED.
Axis Synchronization:
Motion tasks assigned to the SIMOTION D435 execute strictly within state-defined boundaries and cease instantly upon leaving the EXECUTE or HOLDING states.

Limitations and Operational Cautions

Transition Logic Integrity: Never force or override the LPML internal state tags directly in memory. State changes must occur solely via valid command inputs to prevent drive logic desynchronization.
Safety Integration: The PackML state machine is an operational management layer, not a safety controller. Emergency Stop (E-STOP) circuits and safety motion functions (STO, SS1, SS2) must be hardwired or processed in a dedicated safety controller/F-CPU independently of the LPML execution state.
Task Allocation on SIMOTION: Ensure that heavy motion path calculations inside the EXECUTE state do not exceed the cycle limits of the assigned SIMOTION execution task, which can trigger system watchdog faults.

Engineer FAQ

Where can I download the official Siemens LPML V3 application example?

The application example "SIMATIC/SIMOTION OMAC PackML V3 Machine and Unit States" is available on the Siemens Industry Online Support (SIOS) portal under Entry ID 49970441.

Can LPML V3 be used on SIMATIC S7 PLCs as well as SIMOTION?

Yes. The standard LPML library structures are designed for cross-platform deployment across SIMATIC S7-1500 controllers and SIMOTION D motion controllers, allowing consistent state handling across machine platforms.

How does LPML handle custom machine-specific modes?

The library supports standard ISA-TR88 modes (Production, Maintenance, Manual) and provides configuration parameters to define custom user modes while maintaining the underlying standard state machine rules.

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