How to Configure Third-Party PROFIBUS DP Slaves (Siprotec, ABB, Rockwell) in SIMATIC PCS 7

In SIMATIC PCS 7, integrating third-party PROFIBUS DP slaves—such as Siemens Siprotec 7SJ80 protection relays, ABB M2M power meters, or Rockwell 20-COMM-D drives—requires installing device-specific GSD files into the STEP 7 Hardware Catalog and configuring standardized cyclic telegrams. Communication with complex slaves involves mapped register blocks (such as 64 words input). To ensure absolute data integrity, all multi-word registers must be configured with 'Total Length' consistency and read or written in controller logic using standard system functions SFC14 (DPRD_DAT) and SFC15 (DPWR_DAT), or dedicated communication function blocks.

Third-Party Device Integration via Device Description Files (GSD)

Industrial process plants frequently incorporate multi-vendor intelligent electrical equipment:
* The GSD (General Station Description) Standard:
* Electronic data sheet defining slave communication parameters, baud rates, supported telegram structures, and diagnostic byte layouts.
* Installing GSD Files in STEP 7:
1. Obtain official GSD files from the equipment vendor (e.g., Siprotec GSD from Siemens, ABB GSD, Rockwell EDS/GSD).
2. In HW Config, select Options > Install GSD File....
3. Browse to the directory containing .gsd / .gse files and click Install.
4. Select Options > Update Catalog. The third-party devices appear under PROFIBUS DP > Additional Field Devices.

Configuring Siprotec 7SJ80 Protection Relays and Telegram Mappings

The Siprotec 7SJ80 feeder protection relay organizes cyclic PROFIBUS data into fixed Telegram Mappings:

Mapping Architecture:
The internal Siprotec configuration tool (DIGSI) defines which electrical parameters (current $I_A, I_B, I_C$, voltage $V$, active power $P$, trip status) map into cyclic registers.
The Consistency Rule:
Slaves often offer mixed module selections: e.g., 64 words input (with 16 words consistent and 48 words non-consistent).
Siemens Best Practice: Avoid mixing consistency types within the same logical data block. Select modules configured with full consistency across all registers to prevent multi-word tearing of 32-bit floating-point power calculations.

Integrating ABB Power Meters and Rockwell Drives on PROFIBUS

For non-Siemens devices:

ABB M2M Power Meter:
Configured as a modular DP slave exchanging 16 to 32 words of cyclic metering telemetry (voltage, current, power factor, frequency).
Data registers represent integers with fixed decimal multipliers or IEEE 754 floating-point values requiring byte-order verification.
Rockwell 20-COMM-D Drive Interface:
Bridges Allen-Bradley PowerFlex VFDs to PROFIBUS DP.
Exposes standard drive control words (Command / Reference) and feedback words (Status / Actual Velocity).
Mapped directly to motor control blocks in CFC.

Data Consistency Enforcement via SFC14 and SFC15

When reading multi-word consistent blocks from third-party slaves:

Reading Inputs via SFC14 (DPRD_DAT):
pascal CALL "DPRD_DAT" LADDR := W#16#250 // Start address in Hex (e.g., 592 dec) RET_VAL := #RetVal RECORD := P#DB60.DBX0.0 BYTE 32 // Target Data Block buffer
Writing Outputs via SFC15 (DPWR_DAT):
pascal CALL "DPWR_DAT" LADDR := W#16#250 RECORD := P#DB61.DBX0.0 BYTE 16 // Send buffer RET_VAL := #RetVal
Execution Context:
* Call SFC14 and SFC15 in cyclic interrupt OB35 (100 ms) to guarantee deterministic, atomic telemetry updates.

Comparison of Multi-Vendor PROFIBUS Slaves in PCS 7

The table below outlines integration characteristics across typical third-party PROFIBUS DP devices.

Device TypeVendor / ModelData SizeConsistency TypeAccess Method in PCS 7Feeder Protection RelaySiemens Siprotec 7SJ8016 to 64 WordsTotal Length (All)SFC14 / SFC15Power Measurement MeterABB M2M16 to 32 WordsTotal Length (All)SFC14 / Modbus gatewayVariable Frequency DriveRockwell PowerFlex / 20-COMM4 to 8 WordsWord / Total LengthSFC14 / SFC15 / Pcs7DiInMotor ManagementSIMOCODE pro V4 to 16 BytesStandard DPNative SIMOCODE Library

Verification

To confirm that third-party PROFIBUS communication is healthy:
1. In HW Config, verify that all third-party slaves display green checkmarks with zero bus faults.
2. Inspect the physical front panel of the Siprotec relay and ABB meter: confirm that the PROFIBUS communication LED is steady green.
3. In the S7-400 CPU, monitor RET_VAL of SFC14: confirm it returns W#16#0000 (success).
4. In DB60, compare incoming current values against the physical display of the Siprotec relay: verify values match with correct decimal scaling.
5. Disconnect the bus connector: confirm that the CPU triggers OB86 (Rack Failure) and logs a communication failure alarm in WinCC.

Limitations and Operational Precautions

Third-party GSD files do not support automated CFC module driver generation; you must manually program communication calls (SFC14/SFC15) and parse data registers.
Verify byte order (Big-Endian vs Little-Endian); Rockwell and Modbus devices often transmit low byte first, requiring word/byte swap instructions (CAW / CAD) in SCL.
Ensure all third-party devices adhere to standard PROFIBUS termination and shielding rules to avoid bus reflections that degrade adjacent PCS 7 remote I/O.
Always validate final hardware equipment schedules, communication interfaces, and software licensing against the applicable manufacturer catalog and authorized distributor quotation.

Engineer FAQ

Why did SFC14 return error 8090 on the Siprotec slave?

Error 8090 indicates that the logical start address (LADDR) does not exist in HW Config or was not configured with 'Total Length' consistency.

Can I use standard APL channel blocks like Pcs7AnIn for third-party DP slaves?

No. Standard APL channel blocks are designed for modular S7 I/O cards. For third-party slaves, use SFC14 to read data into a DB, unpack values in SCL, and pass them to technological blocks like MonAnL.

What baud rates do third-party PROFIBUS slaves support?

Most modern slaves support up to 12 Mbps with autobaud detection. However, older power meters may be capped at 1.5 Mbps; verify the maximum supported speed in the vendor GSD file.