Siemens SIMOREG DC Master SG70 PROFIBUS DriveES Parameterization

Siemens SIMOREG DC Master SG70 DriveES Parameterization via PROFIBUS: CBP versus CBP2 Failure Mode

Problem Overview

A Siemens SIMOREG DC Master 6RA70 (SG70 frame size, basic-unit firmware v2.0) responds correctly to cyclic PROFIBUS-DP traffic from a SIMATIC S7 PLC. Setpoints are written, actual values are read, and the converter is fully controllable in the process. However, the engineering tool DriveES v5.5 cannot establish an online connection to the same drive for parameterization. DriveMonitor reports a persistent NC — not connected status, and no parameter values are read back into the project.

The fault pattern is asymmetric: a SIMOVERT MASTERDRIVE (AC drive) sitting on the same PROFIBUS segment connects to DriveES without issues. The same PC adapter, the same Set PG/PC Interface, and the same HW Config project both reach the bus. Only the SIMOREG refuses the acyclic class-2 handshake.

The root cause is the SIMOREG's communication module: the drive is fitted with a first-generation CBP (MLFB 6SE7090-0XX84-0FF0) instead of a CBP2 (MLFB 6SE7090-0XX84-0FF5). The CBP does not implement the full DPV1 class-2 acyclic service set that DriveES requires to enumerate and read/write parameters. The CBP2 does, and a hardware swap from CBP to CBP2 restores DriveES connectivity without any software change.

Affected Components and Versions

Symptom Matrix

Root Cause: CBP versus CBP2 Service Profile

The SIMOREG CBP (suffix 0FF0) was designed for DPV0 cyclic operation. It supports process-data exchange (PZD) and a limited parameter-channel (PKW) implementation that was adequate for early SIMOREG commissioning tools. DriveES v5.5 (and later) use the full DPV1 class-2 acyclic services (MSAC2_Read, MSAC2_Write) to enumerate parameter numbers, read parameter values, and write parameter values back. The CBP firmware implements only a subset of those services. DriveES opens a class-2 connection to the slave, requests a parameter directory, and never receives a compliant response. The tool interprets the timeout as a connection failure and reports NC.

The CBP2 (suffix 0FF5) implements:

• Full DPV1 class-1 and class-2 acyclic services.
• PKW 4-word and PKW 8-word buffer modes (parameter-channel length 4 and 8).
• The GSD revision expected by HW Config when the SIMOREG is inserted from the DriveES HW Catalog.
• Improved diagnostic data exposed via the PROFIBUS diagnostics slot.

Once a CBP2 is fitted and the drive powers up, DriveES completes the class-2 handshake within a few seconds, DriveMonitor transitions to ONLINE, and the full parameter tree becomes available for upload, modification, and download.

Why the PLC keeps working on a CBP

Cyclic PZD is implemented on top of DPV0 services in both CBP and CBP2. As long as the PPO type selected in HW Config (1, 2, 3, 4, or 5) matches what the drive expects, the SIMATIC CPU exchanges setpoints and actual values without ever touching the acyclic class-2 channel. The PLC does not care that the CBP cannot enumerate parameters over PROFIBUS, because the PLC writes its own parameter requests via the SFB/SFC acyclic services using the WR_REC / RD_REC mechanism, which is a different path through the slave.

This is why a healthy S7 application coexisting with a dead DriveES link is the diagnostic fingerprint of a CBP-only limitation and not a wiring or address problem.

Diagnostic Procedure

Run the checks below in order before replacing the CBP. Most of the symptoms of a CBP failure can be reproduced by misconfiguration, and the CBP is a field-replaceable part that you want to confirm as the cause before swapping.

1. Verify the PROFIBUS physical layer and station address

• Inspect the PROFIBUS-DP cable and the D-sub connector on the SIMOREG. Confirm that the terminating resistor is ON at the two physical ends of the segment and OFF at every intermediate node.
• Confirm that the bus address set on the SIMOREG matches the HW Config slot. In this case, P918 = 6 (decimal) and the HW Config station address = 6.
• Power-cycle the SIMOREG after a change of P918; the value is latched on power-up.

2. Read the CBP / CBP2 LED

A solid green LED with the PLC running tells you the bus layer is healthy. If DriveES is still NC, the fault is at the acyclic layer or higher.

3. Validate Set PG/PC Interface

Open SIMATIC Manager > Options > Set PG/PC Interface. The access point S7ONLINE must point to the same CP or PC adapter used for the MASTERDRIVE. A misconfigured PC adapter is the most common software-side reason for a single-slave NC state on a bus where other slaves connect.

4. Verify the SIMOREG parameters

Setting P051 = 40 and P927 = 1 is necessary but not sufficient on a CBP. DriveES attempts a class-2 connection before the parameter-level protection is consulted, so a wrong P051 will look identical to a missing CBP2 service from the operator's perspective. Cycle L+/L- (electronics supply) after parameter changes so the new values are latched.

5. Confirm the slave is inserted from the DriveES HW Catalog

In HW Config, the SIMOREG must be inserted as a slave from the DriveES profile in the HW Catalog, not the generic PROFIBUS-DP catalog. The DriveES profile brings the correct GSD and exposes the acyclic parameter channel (PKW). If the slave was added from a generic Siemens catalog, the slot may show only PPO types 1–4 with no PKW slot, and DriveES cannot open a class-2 session because the slave never advertised the acyclic endpoint.

Procedure to re-insert correctly:

1. Delete the SIMOREG slave from HW Config.
2. Open the HW Catalog and navigate to PROFIBUS-DP > Drives > SIMOREG > DriveES profile.
3. Drag the SIMOREG into the PROFIBUS subnet at the same station address.
4. Recompile and download HW Config.

6. Try a known-good CBP2

If a CBP2 is available on site, swap the CBP for the CBP2 with the drive de-energized. Cycle the electronics supply, then re-attempt the DriveES connection. A clean connection on the CBP2 confirms the original CBP as the root cause and you can leave the CBP2 in service.

Step-by-Step Resolution

Prerequisites

• CBP2 communication board, MLFB 6SE7090-0XX84-0FF5.
• SIMATIC STEP 7 v5.5 with DriveES v5.5 SP installed and licensed.
• Online access (PROFIBUS or serial) to the SIMOREG to verify parameters after the swap.
• ESD wrist strap; CBP/CBP2 modules are sensitive to static discharge.
• Documentation of the existing PROFIBUS station address and the active PPO type.

Procedure

1. De-energize the SIMOREG. Open the front cover and identify the electronics box. The CBP/CBP2 occupies slot C of the electronics box.
2. Remove the existing CBP (suffix 0FF0). If a fiber-optic link runs between the basic unit and the CBP, note its orientation; the CBP2 occupies the same slot and uses the same fiber-optic connector.
3. Insert the CBP2 (suffix 0FF5) into slot C. Seat firmly until the retaining clips engage and the board is flush with the surrounding guides.
4. Reconnect the fiber-optic link between the basic unit and the CBP2 if it was detached.
5. Close the front cover and re-apply control power (24 V on terminals L+ / L-). Wait for the CBP2 to complete its self-test; the PROFIBUS LED cycles briefly through red and settles.
6. From the SIMATIC side, open HW Config. Right-click the SIMOREG slave, choose Object Properties > Device Identification, and confirm the device is now reported as a CBP2 module.
7. Open DriveES. In the project tree, double-click the SIMOREG to bring up DriveMonitor. The status indicator transitions from NC to ONLINE within a few seconds.
8. Perform an Upload to PG in DriveMonitor to back up the parameter set. Save the project archive for change control.

Parameters to verify after the swap

Verification

Validate the fix in three layers.

1. Tool layer. DriveMonitor shows ONLINE. Parameter values are read back from the drive and displayed in the parameter tree. No timeouts on individual parameter reads.
2. Bus layer. The PROFIBUS LED on the CBP2 is solid green when the PLC is in data exchange. During a DriveES upload or download the LED may briefly flicker as acyclic traffic passes.
3. Application layer. From DriveES, upload all parameters, modify a non-safety parameter (for example a ramp time), download the change, and verify the new value is active at the drive. Then restore the original value, save the parameter set, and confirm the change persisted across a power cycle.

If any layer fails, revisit the HW Config insertion path and confirm the slave was added from the DriveES profile. A CBP2 inserted from a generic DP catalog exhibits a behavior identical to a CBP inserted from the DriveES profile, so the catalog selection is the most common regression after the swap.

Preventive Measures and Field-Proven Caveats

• Stock a CBP2 spare. CBP modules are legacy; CBP2 is in production, firmware-upgradable, and increasingly hard to find on the used market. Keep at least one CBP2 on the shelf per site with SIMOREG drives.
• Use the DriveES profile in HW Config from the start. New SIMOREG commissioning should insert the slave from PROFIBUS-DP > Drives > SIMOREG > DriveES profile. This loads the correct GSD and exposes the acyclic parameter channel from the first download.
• Repeat the DriveES test after every firmware update on the basic unit. A firmware upgrade on the 6RA70 (for example from v1.x to v2.x) can change how acyclic services are routed and may surface latent limitations of a CBP that previously worked.
• Document bus address, PPO type, and CBP/CBP2 part number in the project hardware list. Future engineers can correlate field behavior with the hardware revision in seconds.
• Have a serial fallback ready. If you must continue using a CBP, use the PMU on the door of the SIMOREG or the X300 / X351 serial interface with DriveMonitor over a serial cable. Acyclic access is fully supported over the serial link even when the CBP cannot expose the class-2 services on PROFIBUS.
• Confirm hardware compatibility before a CBP-to-CBP2 swap on older units. On older 6RA70 units (C98163-A1004-A1-xx hardware) a CBP2 may require an electronics-box update. Verify in the SIMOREG 6RA70 operating instructions before the swap.
• Save the parameter set before and after the swap. U953 = 1 writes the active parameters to non-volatile memory. Skip this step and the next power cycle wipes any unsaved P051 / P927 changes.

Alternate Controller and Platform Notes

TIA Portal

DriveES for TIA Portal (V5.5 SPx and later) uses the same SIMOREG GSD revision as DriveES v5.5. The CBP2 hardware requirement is unchanged. If you migrate from SIMATIC Manager to TIA Portal, do not regress to a CBP — the failure mode is identical and the migration is the right time to replace the module.

Third-party PROFIBUS masters

Any PROFIBUS class-1 master (ABB AC500, Schneider M340, Beckhoff CX with PROFIBUS) will see the CBP or CBP2 identically for cyclic I/O. The acyclic limitation only affects class-2 masters, which includes DriveES, STARTER with DriveMonitor, and most asset-management tools. If you intend to use a third-party asset manager on a SIMOREG, plan for a CBP2.

PROFINET migration

The CBP2 has a PROFINET sibling, the CBE20 (MLFB 6SE7090-0XX84-0FF6). When retiring PROFIBUS segments, swap the CBP2 for a CBE20 and update the controller-side configuration. SIMOREG firmware that supports the CBP2 generally supports the CBE20 as well. The GSD for the CBE20 is shipped with TIA Portal; for SIMATIC Manager you must install the latest HSP for the SIMOREG 6RA70.

Diagnostic Quick Reference

Troubleshooting Matrix