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

Simulating Multi-Axis Camming and Synchronous Motion in NX MCD Without SIMIT

Simulating Multi-Axis Camming and Synchronous Motion in NX MCD Without SIMIT

Yes, multi-axis camming and synchronous motion profiles can be simulated between Siemens automation controllers (such as S7-1500T Technology CPUs or SIMATIC systems) and NX Mechatronics Concept Designer (MCD) without SIMIT. By deploying S7-PLCSIM Advanced, engineers can establish a high-speed direct coupling using either the integrated PLCSIM Advanced API / Softbus interface or by configuring the virtual PLC as an OPC UA Server connected to NX MCD as an OPC UA Client. This bypasses the 30-signal limitation of SIMIT Demo mode and provides full multi-axis virtual commissioning without purchasing a full SIMIT runtime license.

Table of Contents

Executive Summary

Virtual commissioning of complex multi-axis motion machinery—such as packaging machines, flying shears, and synchronized cam conveyors—traditionally pairs Siemens NX Mechatronics Concept Designer (MCD) with SIMIT simulation software acting as intermediate behavioral middleware. However, engineering teams operating under evaluation or cost-constrained conditions encounter the rigid 30-signal limitation of SIMIT Demo mode, which prevents synchronizing more than a single motion axis. It is entirely feasible and supported to simulate multi-axis synchronous camming directly between S7-PLCSIM Advanced and NX MCD without SIMIT. Utilizing the native PLCSIM Advanced runtime API / Softbus driver inside NX MCD eliminates SIMIT license dependencies while delivering deterministic, high-bandwidth signal exchange for multi-axis kinematic validation.

Architecture and Fundamental Mechanics

Understanding how multi-axis synchronization operates without SIMIT requires examining the two direct architectural pathways available between the virtual PLC and NX MCD.

1. Direct PLCSIM Advanced API / Softbus Interface (Recommended)

NX Mechatronics Concept Designer features a built-in native signal adapter for Siemens S7-PLCSIM Advanced. Rather than routing signals through SIMIT or OPC networks, NX MCD directly loads the Siemens.Simatic.Simulation.Runtime.Api.dll shared library:
- The virtual PLC runs inside S7-PLCSIM Advanced on the local workstation memory space (Softbus).
- The Technology Objects (TO_SyncAxis, TO_Cam, TO_LeadingAxis) execute motion interpolation cycles inside the virtual CPU.
- NX MCD communicates directly with the virtual controller's input/output image and data blocks at the simulation time-step frequency.
- Because SIMIT is omitted entirely, no SIMIT tag licensing restrictions exist, allowing dozens of synchronous axes, cam profiles, and I/O points to simulate concurrently.

2. Embedded OPC UA Server Architecture (Alternative)

If cross-network simulation is required (e.g., NX MCD running on a separate CAD workstation from the simulation PLC):
- S7-PLCSIM Advanced is configured to use the 'PLCSIM Virtual Ethernet Adapter' on the physical network.
- The virtual S7-1500 / Technology CPU enables its integrated OPC UA Server on port 4840.
- NX MCD acts as an OPC UA Client, browsing the controller's address space and mapping axis setpoint positions (Position, Velocity) directly to MCD Kinematic Position Controls and Joint Sensors.

Step-by-Step Implementation Procedure

To configure direct multi-axis synchronous cam simulation in NX MCD without SIMIT:

Step 1: Configure Technology Objects in TIA Portal

  1. In TIA Portal, open your project containing the motion controller (e.g., CPU 1515T or CPU 1517T).
  2. Under Technology objects, create:
    - Leading_Axis (Virtual or Real axis, TO_PositioningAxis).
    - Cam_Profile (TO_Cam, defining the cam curve geometry).
    - Follower_Axis_1 and Follower_Axis_2 (TO_SynchronousAxis).
  3. In the follower axis properties, configure Leading value interconnections pointing to Leading_Axis via Cam_Profile.
  4. In program blocks (e.g., OB1 or MC-Interpolation OB92), call MC_CamIn to establish cam synchronization.
  5. Under CPU Properties -> Protection, ensure 'Permit access with PUT/GET communication' and OPC UA accessibility are enabled.

Step 2: Start Virtual Controller in S7-PLCSIM Advanced

  1. Launch S7-PLCSIM Advanced as Administrator.
  2. Under 'Start CPU', choose communication interface:
    - Select PLCSIM (Local Softbus) for fastest single-PC execution.
    - Enter an Instance Name (e.g., Sim_Motion_CPU) and start the virtual controller.
  3. In TIA Portal, select the PLC, click Download to device, select the PLCSIM interface, and download the hardware configuration and motion blocks.

Step 3: Establish Direct Connection in NX MCD

  1. Open your 3D assembly in NX Mechatronics Concept Designer.
  2. Navigate to the Engineering tab -> open the Signal Connection editor.
  3. Click Add External Connection and select PLCSIM Advanced from the driver dropdown menu.
  4. Enter the virtual PLC instance name (Sim_Motion_CPU) and click Connect.
  5. The tag browser opens automatically, displaying all accessible I/O and DB variables.
  6. Map the follower axis setpoint position (Follower_Axis_1.Position) to the MCD Position Control joint, and map encoder feedback back to the PLC.
  7. Start the NX MCD simulation player and run the PLC motion sequences.

Verification

To verify multi-axis cam synchronization:

  1. Kinematic Motion Verification:
    - In TIA Portal, open the Axis Control Panel for Leading_Axis and jog the master axis forward.
    - In the NX MCD 3D graphics view, verify that both follower axes smoothly trace their non-linear cam trajectories in real-time.

  2. Signal Throughput and Synchronization:
    - Observe the MCD simulation diagnostics window; confirm that cycle execution maintains steady 60 fps simulation without frame dropping.
    - Verify that all synchronous axes operate without tripping SIMIT signal ceiling alarms.

Limitations and Operational Precautions

Operational limitations and precautions:

  1. Physics Fidelity vs Behavioral Modeling: Direct PLCSIM Advanced coupling provides kinematic joint control. However, complex behavioral physics (such as hydraulic line compressibility, thermodynamic boiling, or complex sensor signal conditioning) that SIMIT provides must be modeled manually in MCD or PLC code.
  2. Simulation Time-Step Synchronization: Ensure the simulation time step in NX MCD matches or divides evenly into the TIA Portal MC-Servo / MC-Interpolation cycle clock (e.g., 4 ms) to avoid motion jitter.
  3. Licensing Distinction: S7-PLCSIM Advanced requires a valid engineering license (SIMATIC S7-PLCSIM Advanced). Virtual commissioning in NX MCD requires the NX Mechatronics Concept Designer license feature.
  4. Commercial Disclaimer: Verify all software licensing entitlements, motion control packages, and PLCSIM options with an authorized Siemens distributor or the Siemens Industry Mall.

Engineer FAQ

Why does SIMIT Demo mode restrict multi-axis simulation?

SIMIT Demo mode enforces a hard ceiling of 30 total signals. Because each motion axis requires 10 to 15 control, setpoint, and feedback tags, controlling two or more axes exceeds the 30-signal threshold.

Does connecting NX MCD directly to PLCSIM Advanced require OPC UA?

No. NX MCD includes a native PLCSIM Advanced API / Softbus driver that communicates directly via workstation shared memory, bypassing both SIMIT and OPC UA.

Can non-linear cam curves (TO_Cam) be simulated accurately this way?

Yes. The motion profile is computed inside the virtual S7-1500T Technology CPU, and setpoint positions are streamed directly to NX MCD kinematic joints every simulation time step.

Is S7-PLCSIM Advanced included with standard TIA Portal STEP 7 Professional?

No. Standard PLCSIM is included, but S7-PLCSIM Advanced (which provides API access, Softbus, and virtual networking) is a separately licensed product.

What is the advantage of using SIMIT if direct connection is possible?

SIMIT provides advanced plant behavioral modeling (sensor dynamics, material flow, electrical drive modeling, hydraulic physics) that neither the PLC nor MCD provides on its own.

Technical References

Related Articles

Related Tags

  • NX MCD
  • PLCSIM Advanced
  • Camming
  • Synchronous Axis
  • Virtual Commissioning
20 respuestas