Integrating SINAMICS DCM with SIMOTION D425-2 over PROFIBUS DP

Overview: Communication Options Between SINAMICS DCM and SIMOTION D425-2 DP

The SINAMICS DCM is a scalable DC drive system built on a SINAMICS platform Control Unit (CUD) and is designed for both simple and demanding DC drive applications. The SINAMICS DCM product family is mechanically and electrically distinct from the SINAMICS S120 modular drive system, and this distinction is critical when planning a connection to a SIMOTION motion controller such as the D425-2 DP.

Three formal communication paths exist between the SINAMICS DCM CUD and a SIMOTION D425-2 DP motion controller:

1. PROFIBUS DP – integrated on every SINAMICS DCM CUD. No additional option card is required. This is the path used in the configuration discussed in this article.
2. PROFINET – available only when a PROFINET option card (CBE20 or PN-CBA) is installed in the CUD option slot. This is a hardware option, not a firmware upgrade.
3. DRIVE-CLiQ – the SINAMICS DCM exposes the X100 and X101 DRIVE-CLiQ ports on the CUD front panel, but these ports are reserved for connecting SINAMICS S120 components such as Sensor Modules (SMC/SME), Terminal Modules (TM), and Active Line Modules. DRIVE-CLiQ is not a peer interface for SIMOTION and cannot be used to integrate a SINAMICS DCM into a SIMOTION D425-2 project.

Why DRIVE-CLiQ Is Not Available for SINAMICS DCM

SIMOTION D controllers (D410, D425, D435, D445, D4x5-2) are deeply integrated with SINAMICS S120 and SINAMICS S210 drives via DRIVE-CLiQ. This is the topology for which the SIMOTION SCOUT/TIA Portal libraries (TO_DriveAxis, TO_SynchronousAxis, TO_PositioningAxis, TO_Cam, TO_CamTrack) are pre-wired. The same wiring assumes that the drive object (DO) of a Servo or Vector drive is reachable on DRIVE-CLiQ and that the controller can read out topology data, encoder values, and DO parameters via the drive object itself.

The SINAMICS DCM, although it carries X100 and X101 DRIVE-CLiQ connectors on the CUD, is a DC converter with a closed control loop on the armature and (optionally) the field. It does not expose a drive object that matches the SINAMICS S120 Servo/Vector object model. The DRIVE-CLiQ ports on the DCM are present to allow the CUD to be connected to higher-level SINAMICS S120 components when the DCM is being used as a section drive in a line-up topology, not to act as a SIMOTION peer drive.

Consequences for the project:

• No SIMOTION TO_DriveAxis pre-instantiation path.
• No automatic DRIVE-CLiQ topology discovery by SCOUT for the DCM.
• No Siemens-validated positioning telegram 102/103/105 (these are S120-specific and presuppose DSC – Dynamic Servo Control).
• Free telegram configuration (telegram 999) plus a free interconnection of process data is the engineering reality.

Identifying the Hardware: MLFB 6RA8031-6DV62-0AA0

The MLFB in the source question is 6RA8031-6DV62-0AA0. Decoding the Siemens order number structure:

What this means for PROFIBUS integration:

• PROFIBUS DP is already integrated on the CUD – no additional hardware is required for the controller link.
• If a later migration to PROFINET is desired, a CBE20 PROFINET interface module must be retrofitted into the option slot of the CUD; the order number for that card is determined by the DCM build state.
• Confirm on the nameplate that the rated armature current, field current, and supply voltage match the connected motor and transformer before commissioning; the PROFIBUS configuration itself is independent of the power section rating.

PROFIBUS DP Interface on the SINAMICS DCM CUD

The PROFIBUS DP interface on the SINAMICS DCM is the CUD's X126 connector (9-pin D-sub, female, on the CUD front panel). Pin assignment follows PROFIBUS IEC 61158 / EN 50170:

PROFIBUS DP segment rules that must be observed:

• Cable: PROFIBUS Type A cable, 0.64 mm² (≈ 20 AWG) conductor, characteristic impedance 135–165 Ω at 3–20 MHz.
• Baud-rate / max segment length (Type A, without repeaters): 9.6 kbit/s to 187.5 kbit/s – 1000 m; 500 kbit/s – 400 m; 1.5 Mbit/s – 200 m; 3 Mbit/s – 100 m; 6 Mbit/s – 100 m; 12 Mbit/s – 100 m.
• Termination: 220 Ω termination at both line ends, with the bus terminator switch on the last device. The CUD connector does not include an integrated, switchable bus terminator; an external PROFIBUS connector with a switchable terminator (e.g., Siemens 6GK1500-0FC10) must be used for the line-end device.
• Maximum of 32 nodes per PROFIBUS segment; with repeaters, up to 126 nodes total per PROFIBUS network.

PROFINET Option as an Alternative

If the SIMOTION side is changed to a PROFINET controller (D425-2 PN or a SIMOTION D4x5-2 with the PN variant), the SINAMICS DCM can be equipped with a CBE20 PROFINET interface module in the option slot of the CUD. The CBE20 is recognized by the CUD firmware and exposes two PROFINET ports (X1400 P1, X1400 P2) for line or ring topologies.

The CBE20 option:

• Supports PROFINET RT (real-time) class 1, conformance class B.
• Permits PROFIsafe only when the additional PROFIsafe address is configured in the CUD and the corresponding slot is mapped in the SIMOTION project.
• Does not enable DRIVE-CLiQ peer communication to SIMOTION. The SIMOTION controller still talks to the DCM through PROFINET, not DRIVE-CLiQ.

PROFIBUS Telegram Selection for the DCM

SINAMICS drives (including the DCM) use a telegram concept where parameter p922 selects the standard PROFIBUS telegram. The DCM supports the common Siemens telegrams used across the SINAMICS family, with the practical limitation that the DCM does not support encoder-1/encoder-2 DSC telegrams (102/103/105) – those telegrams are servo-specific and require DRIVE-CLiQ-resident encoder data.

For a SIMOTION D425-2 DP controlling a SINAMICS DCM, the engineering reality is:

1. Start with a standard telegram if the motion controller only needs speed setpoint + 16-bit status/control (e.g., telegram 2 or 3). This is the fastest path to a working bus.
2. Use telegram 999 if the SIMOTION application needs precise torque/armature-current control, n-set smoothing, ramp-function generator control, or a feedback signal beyond the standard status word. The free PZD slots are connected in the SINAMICS expert list via p2051[x] (send) and p2060[x] / p2050[x] (receive).
3. Never assume a SIMOTION TO_DriveAxis can directly map a SINAMICS DCM with telegram 1/2/3/4. The TO expects a Servo/Vector drive object. For the DCM, the SIMOTION project will typically use a virtual axis or encoderless positioning axis with I/O mapping of the PROFIBUS PZD words. Field engineering frequently uses a TO_PositioningAxis with a separate SIMOTION-side actual value source, and treats the DCM as a current/speed follower.

SIMOTION D425-2 DP Hardware and Project Setup

The SIMOTION D425-2 DP is a SIMOTION D4x5-2 series controller in the DP (PROFIBUS) variant. The PROFIBUS interface is on the front-panel D-sub connector X136, with two connectors labeled P1 and P2 to allow daisy-chaining. Either P1 or P2 can be the master toward the SINAMICS DCM; the other can be used for distributed I/O or additional drives.

SIMOTION D425-2 DP slot rules for the PROFIBUS master interface:

• One PROFIBUS DP master interface is supported per D425-2 (X136). The P1 and P2 connectors are electrically the same bus segment; they exist for physical wiring convenience (avoiding T-connectors).
• Maximum 32 slaves per segment, up to 126 slaves total in the network.
• Maximum 12 Mbit/s baud rate, set on a per-segment basis. The SINAMICS DCM supports 9.6 kbit/s to 12 Mbit/s.

Project configuration is performed in SIMOTION SCOUT (with the SINAMICS DCM as a PROFIBUS DP slave inserted from the GSD file SIEM80F2.GSD for the CUD, or via the SCOUT device library) or in TIA Portal with the SIMOTION option. For most legacy installations, SCOUT remains the engineering tool of choice.

Step-by-Step PROFIBUS Integration Procedure

The following sequence assumes SCOUT as the engineering tool and a SIMOTION D425-2 DP at PROFIBUS address 2, with the SINAMICS DCM at address 4. Adjust as required for the actual project.

1. Verify hardware and cabling.
   • Connect the SIMOTION D425-2 DP X136/P1 to the SINAMICS DCM X126 with PROFIBUS Type A cable.
   • Set the bus terminator switch to ON at the two physical line ends. On the SIMOTION D425-2 DP, an integrated bus terminator is available via DIP switch on the front of the module; activate it only if the controller is the line-end device.
2. Set the SINAMICS DCM PROFIBUS address.
   • On the CUD operator panel (PMU) or in STARTER/SCOUT, set p918 = 4 (or any unused address in the segment).
   • Set p2040 (PROFIBUS monitoring time) to 0.1 s as the starting value, and verify that watchdog behavior in p2041 is set as required (typically to "Stop the drive" on communication failure for safety-relevant applications).
3. Select the telegram.
   • Set p922 = 999 (free telegram) for maximum flexibility, or set to a standard telegram (1, 2, 3, 4, 20) if only basic setpoint/actual control is required.
   • For free configuration, set p2071 = 999 to ensure all PZD slots are writable.
4. Configure the PZD interconnection in the SINAMICS DCM.
   • Send (DCM → SIMOTION): p2051[0..n] defines which SINAMICS connector (BICO source) is placed in each PZD word. Typical mapping: status word 1 (r0898) on word 0, actual speed (r0063) on word 1, smoothed armature current (r0027) on word 2, fault word (r2132) on word 3, alarm word (r2131) on word 4.
   • Receive (SIMOTION → DCM): p2050[0..n] defines the SINAMICS connector (BICO sink) for each incoming PZD word. Typical mapping: control word 1 (r0050) on word 0, speed setpoint (input to p1070 main setpoint) on word 1, ramp-function generator input on word 2 if required.
5. Configure the SIMOTION project.
   • Insert the SIMOTION D425-2 DP at PROFIBUS address 2.
   • Insert a PROFIBUS subnet (e.g., PROFIBUS_1) at the D425-2 X136 connector.
   • Insert the SINAMICS DCM on the subnet at address 4. Use the GSD file SIEM80F2.GSD if the device is not in the SCOUT device library, and select the matching slot/telegram assignment.
6. Map the I/O addresses.
   • In the SIMOTION project, navigate to the SINAMICS DCM slave's I/O addresses (e.g., input bytes 256–269 and output bytes 256–269 for a 14-PZD bidirectional configuration). Note these addresses for the technology object mapping.
   • Cross-check that the address range is outside the SIMOTION local I/O and is not double-booked by another PROFIBUS slave.
7. Create the axis / technology object.
   • Create a TO_PositioningAxis in SCOUT with a virtual encoder (or, if a real encoder is wired to the DCM and fed back via a SINAMICS Sensor Module, with that encoder as the position actual value source).
   • In the TO configuration, set the I/O mapping for the SIMOTION-issued control word and the SIMOTION-received status word, and configure the setpoint/actual value word mapping to the PROFIBUS PZD addresses assigned in step 6.
8. Download and commission.
   • Download the SIMOTION project to the D425-2.
   • Download the SINAMICS DCM configuration (from STARTER or SCOUT) to the CUD.
   • Power up in sequence: SIMOTION first, then DCM, then close the line contactor only after the DCM is in "Ready" (r0899.0 = 1) and bus communication is alive.

Free Telegram 999 Configuration for SIMOTION Axis

Because the SINAMICS DCM does not match the SINAMICS S120 Servo/Vector object model expected by SIMOTION's TO_DriveAxis, the engineering is most often performed with telegram 999 and a free PZD mapping. A typical 8-PZD bidirectional assignment:

The full PZD slot count and the SIMOTION-side interpretation must be set identically in both the SINAMICS expert list and the SIMOTION I/O address mapping. Mismatched word counts are the most common commissioning error and result in the SINAMICS DCM issuing F08501 "PROFIBUS configuration error" on the very first cyclic frame.

Diagnostics, Status Words, and Fault Handling

Diagnostic information is available on both the SINAMICS DCM CUD and the SIMOTION side. The CUD has front-panel LEDs for high-level state inspection; the SIMOTION side exposes bus diagnostics via the device diagnostics buffer and SCOUT/TIA Portal online diagnostics.

Common PROFIBUS-related fault codes on the SINAMICS DCM:

Verification and Acceptance Test

After the configuration has been downloaded to both devices, perform a structured acceptance test before handing the line over to production:

1. Bus health check. Confirm green DP LED on the CUD and a non-zero p2042 counter in the SINAMICS parameter tree. Confirm in SCOUT that the SINAMICS DCM slave shows "OK" under device diagnostics.
2. Setpoint sweep at zero speed. From SCOUT, issue a controlled 5% speed setpoint, confirm r0063 (actual speed) tracks, and confirm armature current r0027 is in the expected range. Issue an OFF1 from SIMOTION and confirm the DCM decelerates under its own ramp and drops the line contactor under hard-wired E-stop.
3. Direction polarity check. At a small setpoint, verify that the actual speed sign matches the expected motor direction. Reverse two phases on the field wiring or re-map the sign in p1070 and p1075 if polarity is inverted.
4. Communication loss test. Disconnect the PROFIBUS connector at the CUD. Confirm that the CUD issues F08505 / F01910 within the configured p2040 time, and confirm the line contactor drops as a result of the OFF1 issued by the CUD's own loss-of-bus reaction.
5. Re-connection test. Restore the PROFIBUS connector. Confirm that the CUD self-clears the fault, re-enters the "Ready" state, and resumes cyclic communication without a manual reset (if the configured reaction is "FAULT, no restart inhibit").

Frequently Asked Questions