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

Evaluating Motion Axis Coupling Limits and Licensing Boundaries in SIMIT Demo Mode

Evaluating Motion Axis Coupling Limits and Licensing Boundaries in SIMIT Demo Mode

In SIMIT Simulation Platform (such as V10.1 and V10.2), controlling two or more multi-axis kinematic systems using the NX Mechatronics Concept Designer (MCD) coupling is not possible in SIMIT Demo mode because the project exceeds the strict 30-signal coupling limit. SIMIT Demo mode enforces an absolute ceiling of 30 coupling signals across all input, output, and internal diagnostic tags. A multi-axis MCD model inevitably exceeds 30 signals because each motion axis requires position, velocity, torque, status, and control signals, alongside internal communication heartbeats and time synchronization words. To simulate multi-axis machines, you must purchase and activate a full commercial license—specifically SIMIT Standard or SIMIT Professional—which supports unlimited coupling signals.

Table of Contents

Executive Summary

Virtual commissioning of complex kinematic machinery and automated assembly cells relies on coupling virtual physics engines—such as Siemens NX Mechatronics Concept Designer (MCD)—with real-time controller simulations running in SIMIT Simulation Platform and S7-PLCSIM Advanced. To facilitate initial software exploration, Siemens provides a free 'SIMIT Demo' mode that launches when no license is present in Automation License Manager.

Engineers evaluating multi-axis machine models frequently encounter a frustrating error upon launching a dual-axis simulation: 'Error: Too many coupling signals used in project.' When users inspect their signal list and observe only 28 explicit process tags, they conclude the software is reporting an error in calculation. In reality, SIMIT counts every single data point exchanged across the coupling interface, including invisible internal handshakes, coordinate transformations, and synchronization words. This technical guide explains the architectural signal counting rules enforced by SIMIT Demo mode, analyzes the signal overhead required by NX MCD couplings, details the commercial license packages needed for multi-axis virtual commissioning, and establishes verified procurement guidelines.

Architecture and Fundamental Mechanics

The signal exchange architecture between SIMIT Simulation Platform and external kinematic engines operates through high-speed shared memory and API couplings:
1. SIMIT Demo Mode Boundary Enforcement:
* SIMIT Demo mode is intended strictly for evaluating single-unit basic operations.
* The software kernel enforces a hardcoded restriction: maximum 30 coupling signals total across the entire simulation project.
* If the sum of all configured input signals, output signals, and coupling metadata tags exceeds 30, SIMIT blocks simulation runtime activation and displays: 'Too many coupling signals used in project'.
2. The 28 vs. 30 Signal Discrepancy (Internal Coupling Overhead):
* When configuring an NX MCD Coupling, the user map typically defines visible technological tags: axis position setpoint, actual position, velocity, drive enable, and limit switches.
* For a single axis, this consumes approximately 12 to 14 process signals.
* For a dual-axis system, two axes consume $2 \times 14 = 28$ process signals.
* Crucially, the NX MCD coupling engine automatically injects mandatory internal synchronization and diagnostic signals:
* _sim_time: Real-time simulation timestamp.
* _mcd_heartbeat: Watchdog handshake between SIMIT and the NX graphics thread.
* _cmd_step: Simulation time-step step synchronization command.
* _coupling_status: Inter-process communication health status.
* These 4 internal signals bring the total coupling count to $28 + 4 = 32$ signals, exceeding the 30-signal demo ceiling and triggering an immediate runtime block.
3. Commercial Licensing Architecture:
* Eliminating signal restrictions requires a commercial license managed via Automation License Manager (ALM):
* SIMIT Standard: Removes all coupling signal limitations (supports thousands of signals bounded only by PC RAM) and enables standard PLCSIM and OPC couplings.
* SIMIT Professional: Adds the Component Type Editor (CTE), S7-PLCSIM Advanced coupling, and advanced NX MCD co-simulation features.
* SIMIT Virtual Controller (VC): Licenses emulated S7-300, S7-400, and S7-410 controllers.

Step-by-Step Implementation Procedure

Step 1: Audit Coupling Signal Counts in SIMIT Project

  1. In SIMIT, open your simulation project.
  2. In the navigation tree under Couplings, select your active NX MCD Coupling (or PLCSIM Advanced coupling).
  3. Open the signal mapping table.
  4. Note the count of active input signals and output signals.
  5. Click on Coupling Properties > Advanced Settings: inspect internal communication and time synchronization tags.
  6. Confirm that the total signal count exceeds 30, confirming why SIMIT Demo mode refuses to start.

Step 2: Temporary Workaround for Single-Axis Testing (Demo Mode Only)

If you must evaluate the setup in Demo mode before acquiring a license:
1. Temporarily disable the second motion axis in NX MCD.
2. Unmap all feedback and control signals associated with Axis 2 in the SIMIT coupling editor.
3. Verify that the total signal count (visible signals + internal handshake signals) is 28 or fewer.
4. Start the simulation: verify that the single-axis model executes without signal ceiling errors.

Step 3: Procure Commercial SIMIT Licenses for Multi-Axis Commissioning

  1. For multi-axis virtual commissioning involving NX MCD and S7-PLCSIM Advanced, select the SIMIT Professional software package.
  2. Determine controller emulation requirements:
    * If using S7-1500 controllers: include S7-PLCSIM Advanced licenses.
    * If using S7-400 / S7-410 controllers: include SIMIT Virtual Controller capacity licenses.
  3. Verify delivery format: Online Software Delivery (OSD) or physical USB dongle.
  4. Submit the procurement schedule to an authorized Siemens distributor or configure the order via the Siemens Industry Mall.

Step 4: Transfer Licenses via Automation License Manager (ALM)

  1. Open Automation License Manager (ALM) on the simulation workstation.
  2. Transfer the permanent floating license key (e.g., SIMIT Professional V10.x) from the USB media or OSD download pool to local drive C:.
  3. Confirm that the license status displays OK with license validity Unlimited.

Step 5: Activate Multi-Axis Simulation in SIMIT

  1. Re-open SIMIT: confirm that the title bar no longer displays 'DEMO'.
  2. Re-enable all motion axes in the NX MCD coupling editor.
  3. Click 'Start Simulation': verify that the simulation kernel initializes and coordinates multi-axis kinematics smoothly.

Verification

  1. In SIMIT, inspect the title bar and status bar: verify that the simulation operates in licensed mode without 'DEMO' watermarks.
  2. Open the SIMIT coupling overview: confirm that all 32+ signals for both motion axes report active communication status 'Good'.
  3. In NX Mechatronics Concept Designer, verify that both 3D kinematic axes respond synchronously to position and speed commands generated by the PLC program.
  4. In Automation License Manager, verify that SIMIT Simulation Platform and associated add-ons show active in-use status without license deficits.

Limitations and Operational Precautions

  1. SIMIT Demo mode is hardcoded to a 30-signal maximum; there is no software setting or registry modification that can bypass this limit without a valid license.
  2. S7-PLCSIM Advanced coupling requires SIMIT Professional or SIMIT Ultimate; SIMIT Standard does not support PLCSIM Advanced.
  3. Hardware capacity planning, simulation scale, and software entitlements must be verified prior to procurement. Final license quantities and order numbers must be confirmed with an authorized Siemens distributor or the Siemens Industry Mall.
  4. High-frequency kinematic simulation (less than 5 ms cycle time) requires high-performance multi-core PC hardware to maintain real-time synchronization.

Engineer FAQ

Why does SIMIT Demo block my project when I have only 28 signals?

The 30-signal limit counts ALL signals participating in the coupling. The NX MCD coupling injects mandatory internal synchronization and timestamp signals (_sim_time, _mcd_heartbeat), pushing the total count over 30.

What is the signal limit in licensed SIMIT Standard or Professional?

Licensed SIMIT editions have no arbitrary signal limits. They support tens of thousands of signals bounded only by available computer RAM and processor performance.

Can I control two axes with SIMIT Standard?

Yes, SIMIT Standard supports unlimited signals. However, connecting to S7-PLCSIM Advanced or using advanced co-simulation features requires SIMIT Professional.

Does SIMIT have a 14-day trial mode with unlimited signals?

Yes. When SIMIT is first installed, Automation License Manager provides a 14-day Trial License that unlocks full platform functionality (unlimited signals) for 14 calendar days.

Where can I find the official order numbers for SIMIT Professional?

Official part numbers (MLFBs) are cataloged in the Siemens SIMIT documentation and can be verified through an authorized Siemens distributor or the Siemens Industry Mall.

Technical References

Related Articles

Related Tags

  • SIMIT Demo
  • NX MCD
  • Coupling Signals
  • Motion Control
  • Virtual Commissioning
20 respuestas