Simulating the SINAMICS G120 in TIA Portal with Standard Telegram 1

Engineers commissioning a SINAMICS G120 from a SIMATIC S7-1200 or S7-1500 over PROFINET frequently run into a wall when they try to validate the run-command path, control word, and speed setpoint without physical hardware. The drive does not respond, NSOLL_A stays at zero, and the status word ZSW1 never sets bit 2 Operation Enabled. The root cause is almost always a mismatch between the telegrams the user thinks they are sending and the telegrams the technology object and the drive actually use. This reference walks through the full setup of Standard Telegram 1 in TIA Portal, shows the correct way to bring the TO_SpeedAxis into simulation, and documents the bit mapping and scaling rules so that the G120 finally responds to a run command.

1. Prerequisites

Before touching the telegram, confirm the engineering environment is consistent. Mixing firmware, GSDML, and TIA Portal versions is the most common source of the drive is not responding symptom.

• TIA Portal V16 or later (V17/V18 recommended for current G120 firmware). Startdrive is integrated starting V15.1.
• SIMATIC S7-1500 or S7-1200 CPU with motion-control firmware (F-CPU also valid; T-CPU for SINAMICS Safety not required for this path).
• Control Unit SINAMICS G120 with CU240E-2 PN, CU240E-2 PN-F, CU250S-2 PN, or CU230P-2 PN. The -2 PN suffix is required for PROFINET.
• PM240-2 power module (or compatible PM330/PM340).
• Drive firmware V4.7 SP3 or later (V5.1 for current Startdrive support). Drive objects that match the Startdrive HSP.
• GSDML matching the CU. With Startdrive installed and the HSP for the CU imported, the G120 appears in the hardware catalog; manual GSDML import is only required for non-listed variants.
• PLCSIM Advanced (preferred) for the S7-1500 path; PLCSIM is acceptable for the S7-1200. PLCSIM alone cannot bring a real drive online, but it is sufficient to exercise the TO_SpeedAxis.

2. Standard Telegram 1 PZD Layout

Standard Telegram 1 is the most compact speed-control telegram. It uses four process data words (PZD) - two from the PLC to the drive (controller output) and two from the drive to the PLC (controller input). When you insert the G120 in the device configuration and select Standard telegram 1, PZD-2/2, TIA wires the following layout automatically.

The telegram is the same regardless of whether you wire it through a technology object or send the words directly from a data block. The technology object provides a normalized interface; it converts the engineering units (rpm, %) into the raw 16#0000..16#7FFF range the drive expects.

3. Configuring the SINAMICS G120 in the Project

1. Open the TIA Portal project and switch to the device configuration of the S7 CPU.
2. From the hardware catalog, navigate to Drives & starters → SINAMICS → G120 → ... → CU240E-2 PN (or your variant).
3. Drag the CU onto the PROFINET subnet of the CPU. TIA assigns a default IP and PROFINET device name - leave them for now, they will be reassigned later.
4. Open the device view of the G120 and switch to the Device view → Properties → Telegram configuration tab.
5. Set Standard telegram 1, PZD-2/2 on the PROFINET interface. If a Siemens telegram such as Telegram 352 is shown by default, replace it. Telegram 1 is the only one the TO_SpeedAxis expects for simple speed control.
6. Confirm the slot assignment: Subslot 1 maps to Control Unit / additional PZD; the two PZD in and two PZD out are wired in the order shown above.
7. Save and compile the hardware configuration.

For users without a real CU connected, the device can be added purely as a project object. The G120 will appear in the topology with a yellow warning icon because no real device is reachable. That is expected and is what enables simulation.

4. Inserting and Configuring the TO_SpeedAxis

The technology object is the only object that lets you bring the speed-control loop into simulation without physical hardware.

1. In the project tree, expand the S7 CPU, then Technology objects → Add new object → Motion Control → TO_SpeedAxis.
2. Assign a name, for example TO_G120_Spindle.
3. In the configuration dialog, link the TO to the G120 PROFINET device. The wizard auto-fills the data block name, the axis name, and references to the telegram - verify they match Telegram 1.
4. Open the TO configuration and switch to Hardware interface:
   • Drive telegram: Standard telegram 1, PZD-2/2.
   • Control word / Status word mapping: Siemens telegram 1 preset.
5. Switch to the Mechanics tab and set the load gear, motor encoder, and any mechanical conversion. For simulation only, leave Encoder type at Simulation.

The most important step is enabling simulation mode. The TO will not respond to a run command without it.

1. Open TO_SpeedAxis → Configuration → Simulation.
2. Tick Activate simulation.
3. Accept the warning: No encoder signals are processed in simulation mode; the actual speed is calculated from the setpoint.
4. Download the project to PLCSIM or to the real CPU.

5. Speed Setpoint Scaling: 4000h and p2000

SINAMICS scales the setpoint and the actual speed against the reference speed defined in p2000. The 16-bit value in PZD2 is a normalized representation:

Set p2000 to the reference speed you want at 100% of NSOLL_A. Typical values: 1500 rpm for a 50 Hz motor on a 4-pole machine, 1800 rpm for 60 Hz, or the motor nameplate rpm if you prefer 100% = rated speed.

Quick conversion helpers for the data block or for direct HW writes:

• rpm → NSOLL_A: NSOLL_A = round(rpm / p2000 * 16384)
• NSOLL_A → rpm: rpm = NSOLL_A * p2000 / 16384
• % (signed) → NSOLL_A: NSOLL_A = round(percent * 163.84)

The TO_SpeedAxis hides this conversion. When you call MC_MoveVelocity with Velocity = 750.0 on a 1500-rpm axis, the TO writes 0x2000 (= 8192, = 50%) into NSOLL_A automatically. If you bypass the TO and write the telegram directly, you must apply the formulas above.

6. Control Word STW1 Bit Mapping

The control word in PZD1 follows the PROFIdrive profile (PROFIdrive Application Class 1, AC1). The drive executes a state machine based on the bit pattern; sending individual bits out of sequence causes the drive to refuse the run command. The typical "happy path" bit pattern is 16#047E to 16#047F over a few PLC cycles.

The numeric pattern to send a run command is therefore 16#047F (binary 0000 0100 0111 1111). The pattern to stop (controlled, pulse still enabled) is 16#047E. 16#0000 triggers OFF2 (coast to stop).

7. Status Word ZSW1 Bit Mapping

The status word lets you confirm the state transition. Without bit 2 set, the drive has accepted the run command in principle but is not yet ramping. Without bit 3, the drive has rejected it (fault or missing enable).

The state transition sequence in the real drive (or simulated by the TO) is:

1. Switching inhibited (ZSW1 bit 6 = 1). Drive powers up, waits.
2. Ready to switch on (bit 0 = 1). STW1 = 16#0406.
3. Ready to operate (bit 1 = 1). STW1 = 16#0407.
4. Operation enabled (bit 2 = 1). STW1 = 16#047F. NSOLL_A accepted.

If the TO simulation is correctly set up, ZSW1 bit 2 will set within 1-2 PLC cycles after STW1 reaches 16#047F.

8. PLC Ladder Logic for the Run Command

Even when the TO_SpeedAxis is in charge of the actual telegram, the run command still has to be issued through the TO. The example below shows the canonical SCL block to start the axis in velocity mode and read back the status.

8.1 Tag declarations

VAR
    // Operator inputs
    bStartAxis    : BOOL;      // Run command from HMI
    bStopAxis     : BOOL;      // Coast / ramp stop
    bAckFault     : BOOL;      // Fault reset pulse
    lrSpeedRPM    : LREAL;     // 0..p2000

    // Motion control blocks
    fbMoveVel     : MC_MoveVelocity;
    fbStop        : MC_Stop;
    fbReset       : MC_Reset;
    fbPower       : MC_Power;

    // Status
    bAxisEnabled  : BOOL;
    bAxisError    : BOOL;
    lrActSpeed    : LREAL;
    wStatusWord   : WORD;      // Raw ZSW1, useful for diagnostics
    wZSW1         : WORD;      // Aliased to .StatusWord
END_VAR

8.2 Enable the axis

// MC_Power: enable the drive, leave setpoint control to the TO
#fbPower(
    Axis := TO_G120_Spindle,
    Enable := TRUE,
    EnablePositive := TRUE,
    EnableNegative := TRUE,
    Override        := 100.0
);
#bAxisEnabled := TO_G120_Spindle.StatusWord.X2; // Operation enabled
#wStatusWord  := TO_G120_Spindle.StatusWord;

8.3 Move at velocity

IF #bStartAxis AND NOT #bStopAxis THEN
    #fbMoveVel(
        Axis     := TO_G120_Spindle,
        Execute  := #bStartAxis,
        Velocity := #lrSpeedRPM,
        Direction := mcDirectionPositive,
        Acceleration := 50.0,
        Deceleration := 50.0,
        Jerk := 0.0
    );
ELSE
    #fbStop(
        Axis := TO_G120_Spindle,
        Execute := #bStopAxis,
        Deceleration := 100.0,
        Jerk := 0.0
    );
END_IF;

#lrActSpeed := TO_G120_Spindle.ActualVelocity;
#bAxisError := TO_G120_Spindle.Error;

8.4 Fault reset

#fbReset(
    Axis := TO_G120_Spindle,
    Execute := #bAckFault AND TO_G120_Spindle.Error,
    Restart := TRUE
);

For users who want to verify the run path without the TO, the raw telegram can be sent from a watch table while PLCSIM runs. The example below shows a manual sequence written into a data block called DB_Telegram.

// Word 0 = STW1, Word 1 = NSOLL_A
// 1) Power on, no run:       16#0406, 16#0000
// 2) Ready to operate:       16#0407, 16#0000
// 3) Operation enabled:      16#047F, 16#2000   (= 50% of p2000)
// 4) Stop, ramp down:        16#047E, 16#0000
// 5) Acknowledge fault edge: 16#048F → 16#047E on next cycle

If using the manual approach, you still need the G120 in the hardware configuration so that the slots exist in the process image. The TO is not strictly required to populate the slots, but the hardware must be configured. Without hardware configuration, TIA cannot resolve the telegram addresses.

9. PLCSIM and PLCSIM Advanced Limitations

The discussion specifically calls out that no real drive can be simulated by TIA Portal or PLCSIM. This is technically correct for the drive object itself, but the S7 side can be exercised fully. The matrix below documents what works and what does not.

For a real bench test, use the SINAMICS Startdrive commissioning tool to verify that the CU reaches Run with a manual STW1 cycle before involving the S7 program. The Startdrive control panel writes the same bits the PLC would send and provides immediate feedback on the drive side.

10. Going Online and Reading Status

When the simulation runs and the run command still does not appear to take effect, the most productive workflow is to compare the values PLCSIM actually puts on the wire against what the TO thinks the drive is doing. Use the watch tables below as a starting point.

For the Startdrive path (real drive), the equivalent inspection is under Drive > Communication > Telegram, which displays the raw PZD words and lets you force STW1 from a checkbox list. The control panel is a fast way to confirm the drive itself is healthy before blaming the PLC.

11. Common Faults and Resolution Matrix

12. Verification Checklist

Use this list as the gate before declaring a bench test done.

1. The G120 appears in the device configuration with the correct CU type and firmware.
2. The PROFINET interface is set to Standard telegram 1, PZD-2/2 and the slots are Inserted in the device overview.
3. The TO_SpeedAxis is created and bound to the same PROFINET device/submodule.
4. Activate simulation is checked on the TO configuration.
5. MC_Power is called with Enable = TRUE; the axis reaches Standstill with Operation enabled.
6. STW1 reads 16#047F on the run command.
7. ZSW1 reads 16#0737 or similar healthy state.
8. NIST_A reflects the commanded speed within ramp tolerance.
9. MC_Stop ramps the drive to standstill with ZSW1 bit 2 = 0, bit 1 = 1.
10. MC_Reset on a simulated fault clears the error code to 16#0000.
11. No F0850x or F3000x diagnostics present on the CPU diagnostic buffer.

13. Notes on Variants and Standards

The information above is documented for the CU240E-2 PN and CU250S-2 PN. Variants such as the G120C follow the same Telegram 1 layout but may differ in the Basic Operator Panel and Smart Access integration. The G120D (distributed) requires a PROFINET cable rated for trailing; the telegram layout itself is identical. For drives outside the -2 PN family, verify the supported telegrams in the Startdrive device configuration - older CU230P-2 variants with firmware below V4.5 may not list Telegram 1 by default and require a free telegram assembly.

Two references are useful for parameter deep dives. The SINAMICS G120 Operating Instructions document the bit fields of STW1 and ZSW1 in detail, and the S7-1500 Motion Control Function Manual documents the TO_SpeedAxis state machine. The exact setpoint scaling is from the SINAMICS Parameter Manual, which lists p2000 and the related normalization ranges.