Configuring S7-1500 Motion Control with MM4 Drives via PROFIdrive

1. Overview

Using the S7-1500 (or S7-1200 from firmware V4.1) technology objects with a legacy Siemens MICROMASTER 4 (MM4) frequency inverter — MM420, MM430, or MM440 — is technically feasible when the drive is configured as a PROFIdrive device and the cyclic telegram is restricted to Standard Telegram 1. The motion-control function blocks in the S7-1500 CPU (MC_Power, MC_MoveJog, MC_MoveVelocity, MC_Home, etc.) operate on the process data of that standard telegram; they do not consume or interpret any PKW channel. Parameter access for commissioning or runtime changes must be handled acyclically through the DPV1 (PROFIdrive acyclic) channel using dataset 47, which is exposed by the PLC's RDREC / WRREC instructions.

2. Compatibility: MM4 Family and S7-1500 Motion Control

PROFINET connectivity on the MM4 family is only available on the MM440 with the Ethernet option module; MM420 and MM430 are PROFIBUS-only when networked. The S7-1500 Motion Control function does not differentiate between PROFIBUS and PROFINET as long as the PROFIdrive profile is active and Telegram 1 is selected.

3. Prerequisites

1. CPU firmware: S7-1500 with Motion Control technology (any S7-1500 supports speed-axis technology objects; S7-1500T adds positioning and synchronous axes). Reference: S7-1500 Motion Control overview in the TIA Portal documentation.
2. TIA Portal version: V15.1 or later (V17+ recommended for current GSD/GSDML handling of legacy MM4).
3. MM4 GSD / GSDML file: Installed in TIA Portal (e.g., SIEM8110.gsd for MM4 PROFIBUS, or the corresponding PROFINET GSDML for the MM440 Ethernet option).
4. MM4 parameter assignment: The drive must be parameterized for PROFIdrive telegram 1 and the appropriate control word source must be set (e.g., P0700 = 6 for command source = PROFIBUS, P1000 = 6 for setpoint source = PROFIBUS on MM420; analogous parameters for MM430/MM440).
5. DriveLib (optional): The Siemens DriveLib library documents the speed-setpoint mode over Telegram 1 in detail and is a useful companion to the TIA Portal online help.

4. Telegram Selection and PROFIdrive Configuration

Telegram 1 is the canonical PROFIdrive setpoint/actual-value telegram and is universally supported on MM4 inverters. Its structure:

MM4 parameter assignment for Telegram 1:

• P0927 = 1 — parameter set change-over via fieldbus (PROFIdrive profile enabled).
• P0700 = 6 — command source = PROFIBUS/PROFINET.
• P1000 = 6 — setpoint source = PROFIBUS/PROFINET.
• P2000 — reference speed in RPM (defines the normalization for NSOLL/NIST).
• P1082 — maximum frequency (should match or exceed P2000 × p / 60).
• Ramp times P1120 / P1121 — set to match the mechanical system's inertia.

In the TIA Portal device configuration, after inserting the MM4 from the hardware catalog, open Properties → Drive → Telegram configuration and select Standard Telegram 1. The technology object automatically recognizes the assignment when Drive type = PROFIdrive is selected under TO Configuration → Hardware interface → Drive → Drive.

5. Technology Object Configuration in TIA Portal

Three technology object types are relevant for VSD-based motion:

Recommended wiring for TO_SpeedAxis:

1. Insert a new TO_SpeedAxis under Technology objects → Motion Control.
2. In the axis configuration, set Hardware interface to the PROFIdrive telegram of the MM4 (TIA Portal auto-fills STW1 → Bit 0..15 mapping for the MC_Power control signals).
3. Assign the telegram to the drive by selecting the drive I/O addresses as the setpoint / actual value source.
4. Set Maximum speed / reference speed identical to the value entered in P2000 on the MM4. Mismatched normalization is the single most common commissioning error.
5. Select the encoder source — for VSD control the encoder (if present) is typically not connected to the drive's encoder interface but to a high-speed counter on the PLC, which then feeds the TO_SpeedAxis as an external encoder.
6. Compile the project; if no errors are reported, download to the CPU.

6. Programming Motion Control Instructions

The Motion Control instructions are part of the PLCopen standard and live in the Technology Objects library. The basic call structure for a speed-axis jog test in Structured Text is:

// Axis enable
MC_Power(
    Axis := SpeedAxis_1,
    Enable := bEnableDrive,
    EnablePositive := TRUE,
    EnableNegative := TRUE,
    Override := 100.0,
    Busy => bPowerBusy,
    Status => bPowerStatus,
    Error => bPowerError,
    ErrorID => wPowerErrorID);

// Jog operation
MC_MoveJog(
    Axis := SpeedAxis_1,
    JogForward := bJogFwd,
    JogBackward := bJogBwd,
    Velocity := 50.0,
    Acceleration := 100.0,
    Deceleration := 100.0,
    Jerk := 0.0,
    Busy => bJogBusy,
    CommandAborted => bJogAborted,
    Error => bJogError,
    ErrorID => wJogErrorID);

// Homing on a position-controlled axis (requires encoder feedback to PLC)
MC_Home(
    Axis := PositionAxis_1,
    Execute := bHomeStart,
    Position := 0.0,
    Mode := MC_HOMING_ABSOLUTE_SETTING_POSITION,
    Done => bHomeDone,
    Busy => bHomeBusy,
    Error => bHomeError,
    ErrorID => wHomeErrorID);

For a homing sequence on a VSD-driven axis, the PLC must be the master of the position loop. The MM4 only closes the speed loop via its V/f or vector controller; the PLC closes the position loop by reading the actual position (e.g., from an SSI or incremental encoder on a fast input module, or from a PROFIdrive encoder that the MM4 is configured to forward in a free PZD slot — which then breaks the technology-object auto-binding).

7. Acyclic Parameter Access (DPV1 Dataset 47)

The S7-1500 Motion Control function does not expose the MM4's internal parameter set (e.g., P0700, P2000, fault memory). To read or write parameters, use the PROFIdrive acyclic channel on top of the cyclic PROFIBUS/PROFINET connection:

Request frame for reading parameter 0x0001 (P0001) from the MM4:

• Function: 0x01 (read request)
• Drive reference: 0x01 (logical drive number, always 1 on MM4)
• Parameter number: 0x0001
• Subindex: 0x00
• Length: 1 word (16-bit value for MM4 non-array parameters)

The function blocks RDREC and WRREC use the slot/subslot of the MM4 head module as the IO address. A typical call:

// Read parameter P0001 from MM4
wStatus := RDREC(
    REQ := bTrigger,
    ID := dwIoAddress,    // HW identifier of the MM4 slot
    INDEX := 47,          // DPV1 parameter channel index
    MLEN := SIZEOF(rdData),
    VALID => bValid,
    BUSY => bBusy,
    ERROR => bError,
    STATUS => wStatus,
    LEN => dwLen,
    RECORD := rdData);    // byte array; first 4 words = PROFIdrive parameter request header

For multiple parameters or repeated access, the DriveLib library provides pre-built FBs (e.g., FB287-family wrappers) that handle the byte-ordering and DoId (drive object) mapping for you.

8. VSD vs Servo: Control Quality Considerations

A VSD such as the MM4 is fundamentally a speed/flux controller, not a position controller. The position loop — when present — lives in the PLC. Implications:

• Sample time: Position-loop update is bound to the S7-1500 MC cycle (1 ms typical, 4 ms minimum). SINAMICS S120 with PROFINET IRT can achieve 250 µs.
• Following error: Expect a steady-state following error of several encoder increments on a high-inertia load, and overshoot during emergency stops that a servo with internal pre-control would not produce.
• Tuning effort: The position controller's P-gain must be de-tuned aggressively (typical Kp ≤ 5 with default 1 ms cycle on a low-inertia axis). Velocity feed-forward can be added in the TO to reduce following error.
• Mechanical compliance: Couplings with backlash or torsion will be amplified at the position loop's corner frequency. Use a stiff drive train.
• Safety: Without a SIL-rated STO circuit on the drive side (MM4 does not support STO), the motion is limited to PL d / SIL 2 with a contactor-based stop category. SINAMICS G120 with CU250S-2 supports STO over PROFIsafe.

The rule of thumb from the field: an MM4-driven position axis is appropriate for low-dynamic applications such as turntable indexing, slitter positioning, conveyor indexing with cycle times ≥ 2 s, and is unsuitable for high-speed camming, electronic gearing, or flying saw patterns.

9. SINA FBs vs Standard Motion Control

The SINA_SPEED (FB285), SINA_POS (FB284), and SINA_CTRL (FB286) blocks are part of the Siemens DriveLib and were developed for SINAMICS drives only. They depend on drive-side SINAMICS-specific telegrams, alarm handling, and parameter numbering (PROFIdrive DoId mapping is non-trivial on MM4). Concretely:

For MM4, use the standard MC instruction set. If a custom application requires SINA-style features (e.g., extended ramp generator on the drive side), implement them on the MM4 directly via parameter assignment and expose them as fixed bits in the telegram.

10. Verification and Diagnostics

1. TO online diagnostics — Right-click the technology object in TIA Portal → Online & Diagnostics. Verify the axis is in Operational state, no Configuration error is present, and the cyclic data is exchanged (drive heartbeat toggles).
2. Watch table — Force STW1 bits: 047E (OFF1 = 0, ready), then 047F (ON command). The MM4 should accelerate to the setpoint.
3. Fault code mapping — If the MM4 trips, the ZSW1 fault bit (bit 3) and the fault number are visible only via the acyclic channel; the cyclic telegram does not carry the fault code. Read fault r0947[0] via RDREC with index 47.
4. Trace — Use the S7-1500 trace to record NSOLL and NIST over time. A correctly-tuned axis shows NIST tracking NSOLL within a 2% band during the ramp.
5. PROFIdrive diagnostics — In the CPU's online view, navigate to Distributed I/O → MM4 → Diagnostics to read the bus state and any PROFIdrive alarms.

11. Limitations and Field-Proven Caveats

• The MM4 has no integrated position controller comparable to a SINAMICS Basic Positioner. Homing, positioning, and synchronous functions all live in the PLC's technology object — and inherit its cycle time and tuning limits.
• The MM4 family is in discontinued / spare-part phase for new installations in many regions. Use MM440 only for new MM4-based motion projects; MM420/MM430 have been phased out and spare parts are restricted.
• PROFINET is supported only on MM440 with the Ethernet option module. MM420 and MM430 are PROFIBUS-only.
• The technology object does not validate that the drive has the encoder source expected by the TO configuration. If the encoder is wired to the drive terminal block (MM4 encoder interface) but the TO actual value is set to "Drive telegram", no error is raised at compile time — the axis simply runs open-loop.
• Cyclic I/O cycle of the technology object must be ≤ the MM4 ramp time. If the MC cycle is 4 ms but the MM4 ramp is 0.1 s, the PLC will generate thousands of setpoint changes that the drive cannot follow.
• For PROFINET connections, the SendClock on the PROFINET interface must be selected so that the MM4's PROFINET update time (minimum 1 ms) is met. The S7-1500 supports 0.25–1 ms send clocks; the MM4 will fall back to slower cycles if the configured value is too aggressive.

12. Related Documentation and Standards

• S7-1500 Motion Control — TIA Portal manual collection
• Siemens Industry Online Support — DriveLib and MM4 entry page
• PROFIdrive Profile — PI (PROFIBUS & PROFINET International) profile document, available on profinet.com

Frequently Asked Questions