How to Integrate SINAMICS G120 Drives via PROFIBUS in PCS 7 Without Drive ES Libraries

To integrate a SINAMICS G120 drive (e.g., CU240 or CU230P-2) into SIMATIC PCS 7 via PROFIBUS-DP without purchasing the Drive ES PCS 7 library, engineers can utilize standard GSD telegrams (such as Telegram 352 or Telegram 20) with direct peripheral addressing. In HW Config, insert the G120 from the standard PROFIBUS catalog and assign standard Telegram 352 (6 PZD words). In CFC, use standard APL channel drivers or custom SCL blocks to assemble the PROFIdrive Control Word 1 (STW1) and 16-bit speed setpoint (NSOLL_A scaled 0 to 16384 for 0% to 100%). Commanding STW1 = 16#047E (Ready to switch on) followed by STW1 = 16#047F starts the drive, while incoming words provide Status Word 1 (ZSW1), actual speed (NIST_A), motor current, and torque.

Drive ES PCS 7 Library vs Direct PROFIdrive GSD Telegrams

When connecting variable frequency drives (VFDs) to SIMATIC PCS 7, engineers typically choose between two engineering methodologies:

1. Drive ES PCS 7 Add-on Library (Automated Integration)

Siemens offers the commercial Drive ES PCS 7 software package containing specialized function blocks (e.g., DRIVE, FbDrive, and APL integration blocks) and pre-built WinCC faceplates. It provides automated driver generation in @ charts, acyclic fault buffer uploading, and parameterization via SIMATIC Manager.

2. Direct GSD / Telegram Integration (Zero-License Cost)

When Drive ES licenses are unavailable or when maintaining legacy projects (e.g., PCS 7 V6.1 / V7.x), engineers can integrate SINAMICS G120 drives directly using the manufacturer GSD file:
* Standard PROFIdrive telegrams (Telegram 1, 20, or 352) are assigned directly in HW Config.
* Cyclic control and status words are mapped to standard peripheral input/output words (PIW/PQW).
* A simple SCL or CFC wrapper converts APL motor commands into standard PROFIdrive bit patterns.

Structure of Standard Telegram 352 (6 PZD / 6 PZD)

Telegram 352 is the most widely utilized telegram for variable-speed process drives because it provides essential operating parameters without consuming excessive bus bandwidth:

Setpoint Channel (AS -> Drive, 6 Words Output):
1. PZD1: Control Word 1 (STW1) - 16 boolean command bits.
2. PZD2: Main Speed Setpoint (NSOLL_A) - 16-bit signed integer (16#4000 = 100% rated speed).
3. PZD3 to PZD6: User-assignable process control words (e.g., torque limits, external faults).
Feedback Channel (Drive -> AS, 6 Words Input):
1. PZD1: Status Word 1 (ZSW1) - 16 boolean feedback bits.
2. PZD2: Actual Speed Feedback (NIST_A) - 16-bit signed integer.
3. PZD3: Actual Motor Current (IACT).
4. PZD4: Actual Motor Torque (M_ACT).
5. PZD5: Active Warning Code (WARN_CODE).
6. PZD6: Active Fault Code (FAULT_CODE).

PROFIdrive Control Word 1 (STW1) and Sequence Logic

To start and stop a SINAMICS drive conforming to the PROFIdrive profile, the control word must follow a strict state transition sequence:

Static Enable Mask (16#047E):
* Bit 1 (No Coast Stop / OFF2): Must be 1.
* Bit 2 (No Quick Stop / OFF3): Must be 1.
* Bit 3 (Enable Operation): Must be 1.
* Bit 4 (Enable Ramp Generator): Must be 1.
* Bit 5 (Continue Ramp Generator): Must be 1.
* Bit 6 (Enable Speed Setpoint): Must be 1.
* Bit 10 (Control by PLC): Must be 1 (mandatory 16#0400 to indicate mastership).
* Bit 0 (ON/OFF1): Remains 0.
* The drive is now in 'Ready to Switch On' state.
Start Command (16#047F):
* Toggling Bit 0 from 0 to 1 asserts ON/OFF1.
* The drive main contactor/inverter energizes and accelerates to setpoint according to its internal ramp rate.
Stop Command (16#047E):
* Toggling Bit 0 back to 0 executes an OFF1 controlled ramp-down to standstill.

CFC Interfacing: Connecting Standard APL Blocks to Peripheral I/O

In CFC, a standard APL motor block such as MotSpdCL (Speed-controlled motor) can be connected to the G120 without custom driver packages:

Command Word Assembly:
Use an SCL block or logic gates to combine MotSpdCL.Start with the static enable mask:
pascal IF MotSpdCL.StartAut THEN Output_STW1 := 16#047F; ELSE Output_STW1 := 16#047E; END_IF;
Speed Setpoint Normalization:
Scale the floating-point speed setpoint (MotSpdCL.SpdAut, 0.0 to 100.0%) to standard PROFIdrive integer units:
NSOLL_A := REAL_TO_INT(SpdAut * 163.84); (where 100.0% * 163.84 = 16384 = 16#4000).
Output Routing:
Route Output_STW1 to PQW x and NSOLL_A to PQW x+2 via Pcs7AnOu channel blocks.
Feedback Parsing:
Read PIW y (Status Word) and extract Bit 2 (Operation Enabled = Running feedback) to feed MotSpdCL.FbkRun.

Telegram 352 Parameter and Bit Assignment Matrix

The following table outlines the Telegram 352 structure, scaling factors, and bit functions:

Word IndexSignal NameDirectionData TypeEngineering ScalingPZD 1STW1 / ZSW1Out / In16-bit WordBit 0: ON/OFF1, Bit 10: Control by PLCPZD 2NSOLL_A / NIST_AOut / In16-bit Int16#4000 (16384) = 100% rated motor RPMPZD 3Reserved / IACTIn16-bit Int16#4000 = 100% drive rated currentPZD 4Reserved / M_ACTIn16-bit Int16#4000 = 100% rated motor torquePZD 5Reserved / WARN_CODEIn16-bit WordDirect parameter number (e.g., A07900)PZD 6Reserved / FAULT_CODEIn16-bit WordDirect fault number (e.g., F07801)

Implementing standard telegram structures preserves full drive diagnostics without requiring proprietary software options.

Verification

To verify direct G120 communication in CFC:
1. In HW Config online, verify that the SINAMICS G120 slave indicates 'Normal' on PROFIBUS.
2. In CFC test mode, assert a start command from MotSpdCL; verify that the outgoing control word transitions to 16#047F.
3. Confirm that the drive display shows 'RUN' and that motor speed accelerates to setpoint.
4. Verify that PIW y+2 returns the actual speed (e.g., 8192 for 50% speed) and that IACT registers actual motor amperage.
5. In WinCC, verify that the motor faceplate displays running status and dynamic speed feedback.

Limitations and Operational Precautions

Direct peripheral addressing bypasses the automated CFC Driver Generator; hardware faults (e.g., bus disconnect) must be monitored via SFC 51 (RDSYSST) and wired to MotSpdCL.CSF.
Bit 10 of STW1 ('Control by PLC') must always be asserted (1); if Bit 10 drops to 0, the drive ignores all PLC speed setpoints and commands.
Ensure drive parameter p2000 (Reference frequency / speed) in STARTER matches the maximum engineering scaling used in CFC.
Always validate final license quantities, module availability, and MLFBs against the applicable Siemens catalog and authorized distributor quotation.

Engineer FAQ

Why does the drive not start even though Bit 0 is ON?

PROFIdrive requires an edge transition on Bit 0 (0 -> 1). Furthermore, Bits 1, 2, 3, and 10 must already be 1. If Bit 10 is 0, the drive rejects the start command entirely.

Can I reset a drive fault without Drive ES?

Yes. Toggling Bit 7 of STW1 from 0 -> 1 pulses the fault acknowledge line, clearing transient inverter trip conditions over PROFIBUS.

What is the difference between Telegram 20 and Telegram 352?

Telegram 20 provides 2 PZD words output and 6 PZD words input (fixed monitoring), whereas Telegram 352 provides 6 PZD words bidirectional, allowing torque limiting setpoints.