SIMOREG 6RA7085 PZD4 Status Word Configuration via PROFIBUS

Overview

The SIMOREG DC MASTER 6RA7085-6DV62-0-Z is a fully-digital, three-phase converter from the Siemens 6RA70 family, designed for variable-speed DC motor drives in the power range typical of the 6RA7085 frame. It communicates with a SIMATIC S7 PLC over PROFIBUS DP using the CBP2 communication board installed in slot 1 of the CUD1 (Control Unit, Digital) card. The drive supports the PROFIdrive profile and accepts the standardized Parameter Process Object (PPO) types defined by the PROFIdrive Application Classes.

When the PPO type selected in the drive's PROFIBUS configuration is PPO4 (0 PKW / 6 PZD), the cyclic data exchange consists of six 16-bit process data words (PZD1 through PZD6) in each direction. The user-visible problem in the field is that the drive's PZD4 (status word 2 from drive to PLC) appears to be a "black box" on the S7 side: the receive double-word in the S7 input process image increments or changes, but the engineer cannot determine which internal connector (signal source) is actually being transmitted in that word. This article documents the parameterization path that makes PZD4 transparent to the integrator.

SIMOREG 6RA7085 Communication Architecture

The 6RA7085 uses a slot-based architecture on its CUD1 board:

• Slot 1 (CUD1): Receives the CBP2 PROFIBUS communication board. The CBP2 contains its own processor, runs the drive-side PROFIdrive state machine, and exchanges PZD/PKW with the drive firmware via dual-port RAM.
• Slot 2 (CUD2): Optional second control unit (not used in this drive variant).
• Slot 3 (SBP): Sensor Board (pulse encoder evaluation).
• Power section: Six-pulse or twelve-pulse thyristor bridge with armature and field supply.

For the 6RA7085-6DV62-0-Z order code:

• 6RA7085 = 6RA70 family, frame size 85 (approx. 850 A armature, depending on firmware)
• 6 = Rated supply voltage class
• DV = Engineering/electronics variant
• 62 = Firmware/feature release
• -0-Z = Standard without options (Z suffix denotes engineering customer-specific configuration)

PPO4 Frame Layout (0 PKW / 6 PZD)

PROFIdrive PPO4 contains no Parameter Identifier (PKW) words but reserves the full six-word PZD payload in each direction. The mapping for a SIMOREG 6RA70 in default configuration is shown below. PZD direction is always described from the PLC's perspective: Receive = drive to PLC (telemetry); Send = PLC to drive (command).

Connector numbers K0001-K9999 are SIMOREG's internal signal database. Chapter 12.1 of the SIMOREG 6RA70 Compendium lists every K-number with its source, scaling, units, and function-diagram reference. PZD1 through PZD3 are usually fixed by firmware because PROFIdrive requires STW1/ZSW1 and main process values (speed, current) in those slots. PZD4 through PZD6 are freely re-mappable, which is why PZD4 looks "opaque" unless the engineer queries U734.

The PZD4 Configuration Problem

The root cause of the integrators' confusion is that the drive-side transmission buffer for PZD4 is just a 16-bit wide register. Whatever connector number is written into the connector-mux of the CBP2 appears verbatim in that PZD slot. SIMOREG does not transmit a parameter number, name, or scaling tag alongside the value; it only transmits raw 16 bits. The PLC can therefore see the bits change but has no symbolic meaning unless the integrator independently documents which K-number the drive was told to map.

In the default factory configuration, U734.04 = K0033 (Status word 2), so most healthy drives appear to send ZSW2 by default. However, any commissioning engineer who has re-parameterized U734 to surface a fault word, a power-section status, or a filtered actual value will have changed that mapping. The visible symptom at the PLC is then "PZD4 no longer behaves like ZSW2", which is exactly the scenario described in the field report.

Parameter U734 — The PZD Connector Source Map

Parameter U734 is a six-element indexed parameter (indices .01 through .06, plus .07 and .08 for the second CBP) that defines which internal connector number is transmitted as PZD4 / PZD5 / PZD6 from the drive to the PLC, via the first communication board (CBP at slot 1, also called "CB/TB" in older manuals). Indices .07-.12 perform the same function for a second communication board (CBP2 in slot 2 or USS on COM1/COM2).

The value displayed at U734.04 is a connector number, not a parameter number. Read it using SIMOVIS (drive's serial commissioning tool) under menu Parameters → Free Connectors → U734, or via PROFIBUS acyclic PKW service (only when PPO1/PPO2/PPO3/PPO5 is used — with PPO4 you must use the serial interface, DriveSTAR file, or an external handheld).

Function Diagram Z110 and G183 Reference

The function plan (Funktionsplan) maps are the canonical visual source for SIMOREG parameter-to-signal flows.

• Sheet Z110: "PZD receive from communication board 1". Shows the connector-mux block for each of the six PZD receive words, the index of U734 feeding each mux, and the destination connectors inside the drive. Z110 makes it explicit that PZD4 receive from CBP slot 1 is sourced from the connector number held in U734.04.
• Sheet G183: "Status word 2 (ZSW2) gating". Shows the bit-by-bit composition of the default K0033 (Status word 2) which contains drive-side status bits per PROFIdrive — e.g. "control requested", "fault present", "warning", "speed reached", "current reached", "n-actual within tolerance".

If a commissioning engineer changes U734.04 from K0033 to some other K-number (for example K0051 — power-section status, or K0111 — fault buffer index), G183 no longer applies because the PLC is no longer receiving ZSW2; the new K-number's function plan sheet (often in the G-sheet group) becomes the reference.

CPU 314C-2 DP Integration

The SIMATIC CPU 314C-2 DP (6ES7 314-6CG03-0AB0 / firmware V3.3.x typical for 6RA70 era) integrates a PROFIBUS DP master on its X2 interface. The integrator must:

1. Install the GSD file for the CBP2 communication board in STEP 7 V5.5. The Siemens GSD for the SIMOREG CBP2 is named SIEM811D.GSD (legacy) or the SIMOREG-specific file published with Drive ES.
2. Configure the SIMOREG as a DP slave on the PROFIBUS network with PPO type = PPO4 (0 PKW / 6 PZD).
3. Map the six receive words into an input double-word / input word block, and the six send words into an output block. With consistent-mode configuration (recommended) the I/O is exchanged via SFC14 / SFC15.

Minimal S7 logic for consistent data exchange (OB1 / cyclic):

CALL "DPRD_DAT"      // SFC14 — read consistent PZD from drive
  LADDR  := W#16#100   // configured I-base address of SIMOREG
  RET_VAL:= MW100      // return code; 0 = OK
  RECORD := P#DB10.DBX0 BYTE 12   // 12 bytes = 6 PZD receive words

CALL "DPWR_DAT"      // SFC15 — write consistent PZD to drive
  LADDR  := W#16#100   // configured Q-base address
  RECORD := P#DB10.DBX12 BYTE 12  // 12 bytes = 6 PZD send words
  RET_VAL:= MW102

Inside DB10, the layout becomes:

Step-by-Step Identification Procedure

Use this procedure to determine what is actually being transmitted in PZD4 from drive to PLC.

1. Establish serial access to the drive. Connect SIMOVIS (RS232 on X500 of CUD1) or DriveSTAR via the PC adapter. Confirm baud rate 9600 default, address 1. With PPO4 only on PROFIBUS, the serial port is the only on-line path to U734.
2. Navigate to U734. In SIMOVIS: Parameter tree → Setpoint / actual values → Free connectors → U734. The Parameter Index Editor shows values for indices .01 to .12.
3. Read U734.04. Note the numeric value. Default is 33 (K0033 = Status word 2). Other common field values are 26 (firing angle), 51 (power-section status), 111 (fault buffer pointer), 167 (speed smoothed), 38 (current actual).
4. Cross-reference the connector. Open chapter 12.1 (Connector list) of the SIMOREG 6RA70 Compendium. Look up the connector number found in step 3. Note its scaling, units, and function-plan sheet reference.
5. Verify against the function diagram Z110 to confirm the connector-mux path. Then jump to the connector's native function-diagram sheet for bit/word decoding.
6. Correlate at the PLC. Observe DB10.DBW6 in the S7 online viewer. Toggle known drive states (enable ON/OFF, run/stop, fault injection) and confirm DBW6 changes match the connector definition from step 4.
7. Document in the PLC tag table. Update the HMI / WinCC tag for "PZD4 = ZSW2" (or whatever the actual connector is). This closes the loop and prevents future engineers from re-asking the same question.

Restoring PZD4 to Status Word 2 (Default)

If the integrator wants PZD4 to default back to K0033 ZSW2, execute the following sequence on the drive (in SIMOVIS or DriveSTAR):

// Restore default PZD mapping to status words
U734.04 = 33     // K0033 Status word 2 (ZSW2)
U734.05 = 26     // K0026 Firing angle alpha (typical default)
U734.06 = 27     // K0027 Line voltage actual
U735.04 = 301    // K0301 Control word 2
U735.05 = 302    // K0302 Speed setpoint secondary
U735.06 = 303    // K0303 Torque limit secondary
// Save parameters to non-volatile memory
P051 = 21        // Save parameters to EEPROM on CUD1

Diagnostic and Troubleshooting Matrix

Comparison with ABB RPBA-01 (Generic PROFIBUS PZD Mapping)

The ABB RPBA-01 PROFIBUS DP Adapter follows the same philosophy: the adapter transmits the contents of internal data sets (DS1-DS16) as the PZD payload, where DS1 is typically the Status Word and DS2 the Feedback Word (Reference / Actual). Like SIMOREG's U734, ABB parameter 51.06/51.07/51.08 etc. select which data set is mapped to each PZD slot. Both vendors solve the same problem the same way — the PZD is just a transport slot, and an internal parameter defines the source signal. Engineers familiar with one vendor should map the concept directly onto the other.

Comparison with SINAMICS / Modern PROFIdrive (r2093)

Modern Siemens SINAMICS drives follow the same pattern but parameterize it differently. On SINAMICS, the receive PZD are routed through r2093.0..15 as bit-serial interconnect outputs for the IF1 PROFIdrive controller (the readback view of PZD4 from the controller's perspective). On SINAMICS, the inverse direction (which internal signal lands in PZD4 for transmission) is parameterized via p2051 / p2061 / p8862. On SIMOREG 6RA70, the equivalent of p2051 is U734 (receive mapping). The conceptual mapping is:

Commissioning Verification Checklist

• Drive powers up in state "Ready" (PROFIdrive ZSW1 bit 0 = 1) within 5 s of PROFIBUS cable plugged.
• CBP2 LED "DP" green; "BF" off; "SF" off.
• S7 SFC14 RET_VAL = 0000 for the SIMOREG I-base address.
• DB10.DBW0 (ZSW1) shows expected status (e.g. 0x0337 = Ready + Enabled + n-actual valid).
• DB10.DBW6 (PZD4) interpreted against U734.04 = 33 → matches ZSW2 bit pattern when toggling run/stop.
• Drive responds to DB10.DBW12 (STW1) bits 0,1,2,3 (OFF1, OFF2, OFF3, Enable) within one PROFIBUS cycle.
• Parameter set saved (P051 = 21) and documented in the project archive.

Safety and Functional Notes

If the drive is part of a coordinated multi-drive system where each drive's PZD4 carries a different signal (e.g. one drive's PZD4 = ZSW2, another's = power status), document U734.04 per drive in the drive parameter sheet, not just in the PLC program. This makes the next commissioning pass painless.