S7-1200 Axis Simulation Failure in TIA Portal V16 Motion Control V7

The TIA Portal V16 axis technology object on the SIMATIC S7-1200 exposes a parameter called Simulate drive and encoder under Basic parameters → General → Simulation. Engineers who enable this flag expect PLCSIM-style offline simulation identical to what an S7-1500 controller provides. The technology object accepts the flag (the data block reports .Simulation.Mode = 1) but the axis never starts. The Commissioning control panel stays grey, the Diagnostics tab shows no active items, and the axis DB reports .StatusBits.AxisSimulation = 0 together with .StatusDrive.CommunicationOK = 0. The root cause is an architectural limitation of the S7-1200 Motion Control runtime, not a configuration defect.

1. Problem Statement

Symptom pattern observed on a CPU 1214C DC/DC/DC with a SINAMICS V90 PN servo drive configured as a PROFIdrive axis on Technology Object TO_Axis_1:

• TO_Axis_1.Simulation.Mode = 1 (constant, set by configuration)
• TO_Axis_1.StatusBits.AxisSimulation = 0 (runtime never enters simulated state)
• TO_Axis_1.StatusDrive.CommunicationOK = 0 (no PROFIdrive telegram exchange)
• TIA Portal Commissioning → Monitor all: Master Control → Activate button is greyed out
• Axis control panel does not respond to MC_MoveJog, MC_MoveVelocity, or MC_MoveAbsolute commands

The configuration is committed to the CPU without errors. No diagnostic buffer entry is generated. The user-visible failure is a silent one — the simulation flag is persisted but the runtime state never propagates.

2. Root Cause: S7-1200 Does Not Support PLCSIM for Motion

Per the official Siemens SIMATIC S7-1200 manual entry SIMATIC S7 S7-1200 Programmable controller (ID: 109741593), the S7-1200 Motion Control runtime does not support simulation in PLCSIM or any offline simulation environment. The Simulate drive and encoder flag in the technology object has a different meaning on S7-1200 than on S7-1500:

The Siemens documentation specifies: "The simulation flag on the S7-1200 Motion means that you can simulate with a PLC (which has to be there) the drive and encoder. You need a PLC and then you can simulate your drive and encoder. No real drive or encoder needed here." This statement appears in the S7-1200 Motion Control V6.0 to V7.0 in TIA Portal V16 manual under section 5.4.3.1 Configuration → General → Simulation.

3. Why the Status Bits Stay at Zero

The simulation state machine on S7-1200 Motion Control V7.0 requires the runtime to enter a simulated PROFIdrive or analog communication channel. On a real CPU in RUN mode, the simulation mode is only effective when:

1. The technology object is a Servo Axis with PROFIdrive telegram (e.g., Siemens telegram 1, 2, 3, 5, 102, 105, or 106) or an analog ±10 V interface.
2. The PLC is physically online with the project (no PLCSIM instance).
3. The drive telegram is enabled via StatusDrive.CommunicationOK = 1; in simulation this bit is set by the runtime itself, not by a real telegram.

When the CPU is running on a PLCSIM instance, the runtime never advances the simulation state machine because PLCSIM cannot virtualize the cyclic PROFIdrive/analog channel the motion firmware expects. The .StatusBits.AxisSimulation remains 0 because the state transition Simulation.Mode = 1 → AxisSimulation = 1 is gated by a runtime check that fails in PLCSIM.

4. Functional Difference: S7-1200 vs. S7-1500 Simulation

If you need full offline simulation (no real CPU, no real drive), you must migrate the axis project to an S7-1500 CPU (e.g., CPU 1511-1 PN, CPU 1515-2 PN) and use TIA Portal V16 with PLCSIM V16 or later. The PLC and HMI programs are largely portable; only the technology object configuration and the motion FB parameter mapping need revalidation.

5. Prerequisites for S7-1200 "Simulate Drive and Encoder" Mode

To use the S7-1200 simulation flag correctly (which still requires a real PLC), verify each item before commissioning:

1. CPU firmware: S7-1200 firmware V4.4 or V4.5 (Motion Control V7.0 is bundled with TIA Portal V16 and supports CPU firmware ≥ 4.4). The CPU 1214C DC/DC/DC with order number 6ES7214-1AG40-0XB0 is a typical target.
2. TIA Portal: V16 Update 7 or later (V16.0 base may exhibit UI inconsistencies on the axis commissioning panel).
3. Technology object type: Servo Axis only — POS or TO_ServoAxis. PTO axis (TO_PTO) ignores the flag.
4. Drive interface: PROFIdrive over PROFINET (e.g., SINAMICS V90 PN, S210, S120) OR analog ±10 V interface (e.g., S210 with ANA module, or third-party analog servo).
5. Online connection: PG/PC connected to CPU via PROFINET or Ethernet; the project must be downloaded and the CPU in RUN mode.
6. Drive hardware: The drive does not need to be physically present when simulation is active — the runtime substitutes the position feedback and drive status internally.

6. Step-by-Step: Configuring Simulation Mode Correctly on S7-1200

1. In TIA Portal V16, open the project and navigate to the Technology objects folder.
2. Open the Servo axis technology object (e.g., TO_Axis_1).
3. In the configuration tree, expand Basic parameters → General.
4. Under Simulation, select "Simulate drive and encoder".
5. Compile the project (Ctrl+B or right-click → Compile → Hardware and Software).
6. Download the configuration to the real S7-1200 CPU (online → Download to device).
7. Set the CPU to RUN mode. Verify the RUN LED is solid green and the ERROR LED is off.
8. Open the technology object's Commissioning panel in TIA Portal.
9. Click Monitor all to activate online monitoring of the axis DB.
10. In the Master Control section, click Activate. The button must be enabled — if it is still greyed out, the PLC is not online with the project.
11. Use the jog controls to test MC_MoveJog (positive and negative), then test MC_MoveVelocity and MC_MoveAbsolute from a watch table or motion FB.
12. Verify in the axis DB:
    • .Simulation.Mode = 1
    • .StatusBits.AxisSimulation = 1 (must transition to 1 within 1–2 seconds of CPU RUN)
    • .StatusDrive.CommunicationOK = 1 (runtime-internal OK; real telegram exchange is suppressed)
    • .StatusBits.StandStill = 1 (when no motion command active)

7. Verification Checklist

Use this checklist to confirm simulation mode is active on S7-1200:

8. Migration Path: Moving the Project to S7-1500 for Full PLCSIM Support

When offline simulation is a hard requirement (training, factory acceptance testing, virtual commissioning), the only sustainable path on a Siemens platform is migration to S7-1500:

1. Add an S7-1500 CPU to the TIA Portal project (e.g., 6ES7511-1AK02-0AB0 CPU 1511-1 PN).
2. Copy the technology object configuration. Most parameters transfer directly; verify encoder scaling, modulo settings, and dynamic limits.
3. Update the hardware catalog reference for the new CPU.
4. Reassign the device PROFINET name and IP address.
5. Open PLCSIM V16, instantiate the S7-1500, and download the project.
6. Enable Simulate drive and encoder on the S7-1500 axis TO. The runtime will set .StatusBits.AxisSimulation = 1 in PLCSIM and the Commissioning panel becomes fully interactive.

Refer to the TIA Portal V21 S7-1200 Motion Control commissioning documentation for axis control panel behavior on the latest firmware.

9. Troubleshooting Matrix

10. Common Field Mistakes

• Misreading the simulation flag: Engineers migrating from S7-1500 expect PLCSIM offline simulation. On S7-1200 the flag only suppresses drive hardware requirements — the CPU itself must be online.
• Configuring a PTO axis: The flag is silently ignored. Check the TO type under Basic parameters → General → Drive type. PTO axes cannot be simulated.
• Running TIA Portal in a VM: Even a real S7-1200 CPU connected over the network behaves identically when the project is downloaded directly. The VMware layer only affects PLCSIM licensing and routing, not the on-line behavior with a real CPU. This is not the cause of the greyed-out buttons when PLCSIM is the target.
• Trial license limitations: TIA Portal V16 Trial license does not block axis simulation on a real CPU. It may limit the project runtime to 21 days; download a new project before expiration.

11. Firmware and Software Compatibility

12. Documenting the Finding for Your Project

When the team needs to communicate the limitation to stakeholders, anchor the explanation on these two facts from Siemens official documentation:

1. S7-1200 Motion Control V7.0 manual section 5.4.3.1 explicitly states that simulation is performed with the PLC present (no real drive/encoder required), not offline.
2. PLCSIM does not virtualize the S7-1200 motion runtime. S7-1500 PLCSIM does, and this is the canonical Siemens-supported path for offline virtual commissioning.