Resolving F07552 Fault on Simotion D425 with SMC20 SSI Encoder

1. Problem Overview

The fault F07552 (A) Drive encoder: Encoder configuration not supported is raised on a SIMOTION D425 controller when an external SSI absolute encoder is wired through a SINAMICS Sensor Module Cabinet (SMC20) and the project is downloaded. The fault halts commissioning because it occurs during drive configuration and the affected SINAMICS drive object (SERVO, VECTOR, VECTORGL, or VECTORMV) drops to OFF2 response state. The same project can sometimes read SSI position data successfully on a SIMOTION D410 via connector X23, which makes the failure appear configuration-dependent on the D425 platform rather than application logic.

This document records the field-proven remediation path, including the SMC20/SMC30 hardware selection rule, the parameter cross-check between p0400, p0404, and r0456, and the alternative wiring path on a SIMOTION D410 that allows the same encoder to be read without an external SMC module.

2. Encoder and Hardware Configuration in the Failing Project

The encoder installed in the affected application is a Baumer IVO absolute encoder with the following nameplate data:

The encoder family provides the additional features listed in the device data sheet: Gray or binary code output, electronic zero-point setting, and self-diagnostic bits. The SSI bit count transmitted per cycle is therefore 10 (singleturn) + 12 (multiturn, because 4096 = 2^12) = 22 bits per SSI frame.

The 10 to 30 V supply range is the critical electrical parameter. The encoder is a 24 V-class SSI device and is therefore incompatible with modules that only support 5 V SSI transceivers.

3. SINAMICS Sensor Module SMC20 - Capabilities and Limits

The SMC20 is a SINAMICS Sensor Module Cabinet designed to evaluate incremental and absolute encoders with 1 V_pp sin/cos analog tracks. Per the SIMOTION / SINAMICS sensor module documentation, the SMC20 supports the following encoder families:

• sin/cos encoders without absolute track (SSI signal chain handled via the connected sin/cos tracks).
• Resolvers are not supported on SMC20 (resolvers require SMC10 or SMI10).

The two physical interface constraints that dominate this failure mode are:

1. Voltage class: SMC20 only supports SSI encoders powered at 5 V. The on-board transceiver assumes TTL-compatible SSI clock and data levels, not 24 V RS-422 levels.
2. Connector type: SMC20 has no push-in or screw terminal connector. The SSI / sin/cos signal pair is wired through a 9-pin SUB-D connector on the front of the module. Cables from the encoder must be terminated in a mating SUB-D connector or a Siemens pre-assembled cable (e.g., 6FX8002 series).
A 24 V SSI encoder wired to an SMC20 may not damage the module (the data lines are differential RS-422), but the encoder is powered at the wrong rail and the SSI handshake thresholds are out of spec. The drive detects the configuration as invalid and reports F07552.

4. Fault F07552 - Technical Description

Fault F07552 is a SINAMICS drive-side alarm. Per the SINAMICS S120/S150 List Manual fault description, the value is structured as follows:

Field	Description
Fault value (r0949, decimal)	Bit-encoded encoder configuration mismatch identifier
Low word, low byte	Encoder data set number (EDS index)
Low word, high byte	Component number (PROFIdrive / topology slot)
High word	Function identifier not supported by the active Sensor Module

The high-word function identifiers relevant to this case are:

r0949 high word	Function	Modules that support it
1	sin/cos encoder with absolute track	SME25
3	Squarewave encoder	SMC30
4	sin/cos encoder	SMC20, SMI20, SME20, SME25
12	sin/cos encoder with reference mark	SME20
15	Commutation with zero mark for separately-excited synchronous motors	VECTORMV
23	Resolver	SMC10, SMI10
65535	Other function (compare r0456 with p0404)	—

The acknowledgement class for F07552 is IMMEDIATELY (POWER ON); a warm restart of the drive object does not clear the alarm, the SINAMICS Control Unit (CU320-2 or integrated) must be powered off and back on. The default response is OFF2, which removes the drive from operation immediately and applies a fast stop.

5. Root Cause Analysis

Two independent problems are present in the failing project. Either one is sufficient to trigger F07552.

5.1 Hardware Voltage Mismatch (Primary Cause)

The Baumer IVO GCA2W.A12A101 is specified for 10 to 30 V DC. SMC20 only supports 5 V SSI encoders. The encoder must therefore be wired to a SMC30 Sensor Module, which supports 24 V SSI encoders and exposes both terminal-block and SUB-D interfaces. With the SMC30, parameter p0400 is set to an SSI encoder type and p0404 is left at the SMC30-supported value (function identifier 3, "squarewave encoder", is the bit the SMC30 returns in r0456 for SSI).

5.2 Connector / Wiring Type (Secondary Cause)

Even after the voltage class is corrected, the SMC20 has no spring or screw terminal block. The encoder cable must be re-terminated to a SUB-D connector, or replaced with a Siemens 6FX8002 pre-assembled cable that carries the correct pin-out for SMC20. Many field installations confuse SMC30 terminal blocks with SMC20 because both occupy the same slot in the SINAMICS S120 line-up. The slot itself is mechanically identical; the firmware identifier (read from the module's electronic nameplate) is what differentiates them.

5.3 Parameter Consistency Check

F07552 is fundamentally a parameter-vs-capability mismatch. The drive is requesting a function bit in p0404 that the active Sensor Module does not signal in r0456. The firmware refuses to bring the encoder online until the two are aligned. The only way to silence the alarm without changing the sensor module is to clear the unsupported function bit from p0404; the only way to keep the encoder hardware unchanged is to swap the Sensor Module.

6. Solution: Hardware Migration from SMC20 to SMC30

6.1 Required Material

• One SINAMICS SMC30 (6SL3055-0AA00-5CA2 or application-equivalent variant). Confirm the order code against the active SIMOTION / SINAMICS configuration in the SCOUT / TIA project topology.
• Encoder cable with SMC30-compatible connector on the module end (terminal block or SUB-D, depending on the variant).
• Updated SIMOTION / SINAMICS project reflecting the new module type at the encoder slot.

6.2 Reconfiguration Steps

1. Open the SIMOTION project in SCOUT (or TIA Portal with the SIMOTION option).
2. In the SINAMICS topology view, replace the SMC20 at the encoder slot with the SMC30. Download the new topology to the drive.
3. On the SINAMICS drive object, set p0400 = 9999 (user-defined encoder) and load the encoder data sheet values:
   • p0407[0] = 1024 (singleturn resolution, increments per revolution).
   • p0421[0] = 22 (total SSI bits per frame: 10 singleturn + 12 multiturn).
   • p0422[0] = 12 (number of bits for number of revolutions, i.e. 2^12 = 4096).
   • p0423[0] = 0 (Gray / binary code selection: 0 = binary, 1 = Gray).
4. Verify that p0404 contains only the function bits supported by SMC30 (function identifier 3, squarewave encoder, is the supported bit for SSI on SMC30). Clear any bits that correspond to sin/cos, resolver, or absolute-track-on-sin/cos functions.
5. Read r0456 to confirm the Sensor Module advertises only the bits selected in p0404. The high word of r0949 must not be present in r0456.
6. Power-cycle the SINAMICS Control Unit to clear the existing F07552 alarm (acknowledgement class is POWER ON).
7. Download the SIMOTION program to the D425. The drive should now come up encoder-ready and the SSI position value should be visible in the encoder word (e.g. actualPositionValue on the TO axis).

7. Alternative: Reading the Same Encoder from a SIMOTION D410 X23

SIMOTION D410 (and D4x5-2) controllers expose an on-board encoder input on connector X23. X23 supports a 24 V SSI absolute encoder directly, without an external Sensor Module. The same Baumer GCA2W.A12A101 can therefore be wired to X23 on a D410, eliminating the need for the SMC module entirely.

Use this option when:

• The slot for the SMC module on the SINAMICS line-up is not available.
• The encoder is used for a slow, supervisory position (e.g. tool indexing, valve position) rather than for motor commutation.
• The TO is configured to consume the X23 input directly rather than going through a SINAMICS drive object.

If the application is on a D425 (no usable X23, or X23 reserved for another purpose), the SMC30 path is the correct remediation. If both paths are open, choose the X23 path for simplicity and skip the SINAMICS encoder commissioning step.

X23 is a SIMOTION-side input, not a SINAMICS-side input. Position values arrive in the SIMOTION user program but are not visible in the SINAMICS drive. Closed-loop torque / speed control on a SINAMICS axis cannot be fed from X23; an SMC module is required for that use case.

8. Parameter Reference and Cross-Check Procedure

Use the following procedure to confirm the parameter consistency after any sensor module swap or encoder change.

1. Read r0456[0] on the affected encoder data set. This is the bit mask of functions the active Sensor Module supports.
2. Read p0404[0]. This is the bit mask of functions the project is requesting.
3. Compute the bitwise AND of the two. If the result is not equal to p0404, at least one requested function is unsupported. Decode the unsupported bits against the table in section 4.
4. Read p0400[0] to confirm the encoder type matches the device. 9999 indicates a user-defined encoder and requires the data sheet values to be entered manually in p0407 / p0421 / p0422 / p0423.
5. Read r0949 on a still-active F07552 alarm. The high word identifies the specific function that is unsupported, the low word identifies the encoder data set and component number.

Parameter	Read/Write	Purpose
p0400	R/W	Encoder type selection (e.g. 9999 for user-defined).
p0404	R/W	Encoder configuration effective (function bit mask).
p0407	R/W	Increments per revolution for user-defined encoder.
p0421	R/W	Total number of bits per SSI frame.
p0422	R/W	Number of bits representing the multiturn count.
p0423	R/W	Code type (binary / Gray) for SSI encoders.
r0456	R	Encoder configuration supported by the active module.
r0949	R	Fault value for the active alarm.

9. SMC20 vs SMC30 vs X23 Compatibility Matrix

Feature	SMC20	SMC30	SIMOTION D410 X23
SSI supply voltage	5 V	24 V	24 V
TTL squarewave input	No	Yes	No (SSI only)
HTL squarewave input	No	Yes	No
sin/cos 1 Vpp	Yes	No	No
Resolver	No	No	No
Connector type	SUB-D only	Terminal block and/or SUB-D	Integrated on D410
External module required	Yes (mounted on SINAMICS)	Yes (mounted on SINAMICS)	No (built-in)
Encoder data visible in SINAMICS	Yes	Yes	No (visible in SIMOTION only)

The single line that matters for this fault is the first row: a 24 V SSI encoder cannot be wired to an SMC20. The second row and the connector column reinforce the same point - even if the voltage is corrected, the wiring topology must follow the chosen module.

10. Verification and Commissioning

After the SMC30 swap and parameter update, perform the following checks before returning the machine to production:

1. Bring the drive online and confirm the drive object exits the OFF2 state. No F07552 should be present in the SINAMICS fault buffer.
2. In the SIMOTION axis diagnostics, observe the actual encoder value. Rotate the encoder shaft by hand and confirm the value increments / decrements monotonically across the full 4096-revolution range and wraps correctly at the modulo boundary.
3. Check the encoder status word. Bit "Encoder ready" must be set; bit "Encoder error" must be clear.
4. Check r0456[0] against p0404[0] to confirm the bitwise AND is equal to p0404.
5. Perform a reference / homing run and confirm the absolute position is reproduced without a referenced-but-inconsistent fault.
6. Power-cycle the SINAMICS Control Unit one more time. The fault buffer must remain clear after the cold restart.

11. Related Faults and Edge Cases

F07552 is one of a family of encoder configuration faults. When an SSI encoder is misconfigured, the following may also appear:

• F07551 - Drive encoder: Encoder configuration error (less specific, raised when the encoder data set itself is corrupt).
• F07560 - Drive encoder: Number of increments / resolution error (raised when p0407 or p0421 are inconsistent with the encoder's actual resolution).
• F31118 - Encoder 1: SSI protocol error (raised when the SSI clock rate is set too high for the cable length or when the bit count does not match the connected device).

Edge cases seen in the field:

• An SSI cable longer than approximately 20 m at the default 1 MHz clock rate can cause intermittent F31118 even with a correctly configured module. Reduce p0420 (SSI baud rate) or use a lower-capacitance cable.
• Gray / binary mismatch (p0423) causes the position to read in a non-monotonic, scrambled pattern that may be mistaken for a hardware fault. The drive will not raise F07552 in this case, but the homing result is invalid.
• Connecting a 5 V encoder to an SMC30 works electrically, but the SMC30's supply rail is 24 V. A 5 V encoder fed from a 24 V rail is damaged immediately. Match the supply rail to the encoder nameplate, not to the module type.

12. Frequently Asked Questions

What does SINAMICS fault F07552 mean on a SIMOTION D425?

F07552 ("Drive encoder: Encoder configuration not supported") is raised when a function bit set in p0404 is not advertised by the active Sensor Module in r0456. The high word of the fault value (r0949) identifies the unsupported function; the low word identifies the encoder data set and component number. The default response is OFF2, and acknowledgement requires a POWER ON of the SINAMICS Control Unit.

Why does my Baumer IVO GCA2W.A12A101 fail on an SMC20?

The Baumer IVO GCA2W.A12A101 is a 10 to 30 V SSI encoder - a 24 V-class device. The SMC20 only supports 5 V SSI encoders and exposes a SUB-D connector without a terminal block. The voltage class mismatch and the wiring class mismatch both contribute; either is enough to produce F07552. The remediation is to move the encoder to an SMC30 (which accepts 24 V SSI) or, on a SIMOTION D410, to the on-board X23 input.

Can I keep the SMC20 and just change p0404 to silence F07552?

No. The unsupported function bit in p0404 is set automatically by the encoder type selected in p0400. Clearing the bit forces the drive to ignore a feature the encoder provides and will produce a different alarm at runtime. The correct fix is to match the Sensor Module to the encoder's electrical interface, not to mask the configuration mismatch.

What SSI parameters must I set for the Baumer GCA2W.A12A101 on an SMC30?

Set p0400 = 9999 (user-defined), p0407 = 1024 (increments per revolution), p0421 = 22 (total SSI bits per frame), p0422 = 12 (multiturn bits, for 4096 revolutions), and p0423 = 0 (binary code). The baud rate p0420 should be set no higher than 1 MHz for cable runs up to 20 m, and lower for longer runs.

Can I read the same encoder from a SIMOTION D425 X23 connector instead of an SMC module?

SIMOTION D425 does not provide a usable X23 input equivalent to the D410's. On a D425 the encoder must be wired through a SINAMICS Sensor Module (SMC30 for 24 V SSI, SMC20 for 5 V sin/cos). The D410 X23 path described in this article is only available on D410. If the controller is a D425, the correct fix is the SMC30 path.