Displaying Inverter Temperatures from SINAMICS G120 on WinCC in PCS 7

To display internal SINAMICS G120 inverter temperatures (e.g., maximum power unit temperature r0037[0] and intake air temperature r0037[3]) on WinCC in SIMATIC PCS 7, extend the drive's cyclic fieldbus telegram to include additional process data words (PZD). In STARTER or Startdrive, configure an extended telegram (such as Telegram 352 or a free telegram) and connect BICO parameters r0037[0] and r0037[3] to transmit words p2051[4] (PZD 5) and p2051[5] (PZD 6). In the Continuous Function Chart (CFC), the drive driver block (APL_G120 or FbDrive) outputs these values on pins PCD5Out and PCD6Out. Route these pins to an analog monitoring block (MonAnL) to display calibrated temperatures on WinCC faceplates.

Cyclic Telegram Extension vs Acyclic Parameter Reading

In variable frequency drive applications, monitoring inverter thermal loading is critical for preventing unscheduled drive trips caused by clogged heat sinks, cooling fan failures, or excessive ambient control room temperatures. In SIMATIC PCS 7, standard drive integration typically employs PROFIdrive Telegram 1 (2 PZD In / 2 PZD Out), which transfers only basic control words, status words, and speed setpoint/actual values.

To extract internal drive parameters (such as inverter temperatures r0037[0] through r0037[3]), engineers can either poll parameters acyclically using system function blocks (RDREC / PZD_REC) or extend the cyclic telegram to transmit temperature values continuously. For real-time alarming and trend logging on the Operator Station, extending the cyclic telegram is the most robust and deterministic approach.

BICO Interconnection of Temperature Parameters in STARTER

Siemens SINAMICS G120 converters utilize Binet-Connector (BICO) technology to route internal metrics to communication buffers:

Parameter Identification: Parameter r0037 stores inverter temperatures in degrees Celsius ($^\circ\text{C}$):
- r0037[0]: Maximum power unit semiconductor temperature.
- r0037[1]: Depletion layer / junction temperature.
- r0037[2]: Inverter heat sink temperature.
- r0037[3]: Inverter intake air temperature.
PZD Transmit Word Assignment: To send these values cyclically, map the parameters to the drive's fieldbus transmit interconnections (p2051 array). Setting p2051[4] = 37[0] assigns the max temperature to cyclic word 5 (PZD 5), while setting p2051[5] = 37[3] assigns intake air temperature to cyclic word 6 (PZD 6).

PZD Output Pins on PCS 7 Drive Driver Blocks

In Continuous Function Chart (CFC), dedicated driver blocks (such as APL_G120 from the Drive ES PCS 7 Library or FbDrive FB1797 from the PCS 7 Basis Library) unpack multi-word telegrams:

PCD1Out to PCD4Out: Standard status words, actual speed, actual current, and actual torque.
PCD5Out, PCD6Out, PCD7Out: Auxillary cyclic words configured by the user.

These outputs deliver 16-bit signed integer values. To make them technological and display them on WinCC with high/low alarms, interconnect PCD5Out to an analog monitoring block (MonAnL) and configure scaling.

Comparison of Inverter Telemetry Transmission Methods

The table below contrasts cyclic telegram transmission against acyclic parameter reading for SINAMICS G120 telemetry.

Telemetry MethodTelegram / MechanismUpdate RateAS Controller OverheadWinCC Alarming & TrendingCyclic Extended Telegram (PZD 5/6)Telegram 352 or Free Telegram (p2051)Cyclic (Every OB35 scan)Minimal (Direct peripheral I/O)Optimal: Instant alarm annunciation and smooth trendsAcyclic Reading (RDREC / SFB52)Data Record 47 (Parameter Channel)Asynchronous (1 to 5 seconds)High (Consumes communication jobs)Good for non-critical periodic reportingHardwired Analog OutputG120 onboard analog output terminalContinuous 4-20mA signalConsumes physical I/O cardHigh wiring cost; redundant when fieldbus existsDrive ES Drive FaceplateDrive ES SIMATIC Manager ToolOn-demand operator clickZero (Direct engineering channel)Manual diagnostic view; no automated OS alarms

Step-by-Step Procedure to Display Inverter Temperatures

Follow this procedure to configure cyclic temperature reporting from a SINAMICS G120 to WinCC:

Reconfigure Drive Telegram in HW Config:
- In STEP 7 HW Config, open the S7-400 station containing the G120.
- Replace the standard Telegram 1 with Telegram 352 (6 PZD In / 2 PZD Out) or a Free Telegram with 6 input words.
- Record the hardware start address (e.g., input words IW 512 to IW 523). Save and compile HW Config.
Map BICO Parameters in STARTER / Startdrive:
- Connect online to the G120 using STARTER.
- Open the communication configuration: set parameter p0922 = 352 (Telegram 352) or p0922 = 999 (Free telegram).
- Set parameter p2051[4] = r0037[0] (Inverter max temperature to PZD 5).
- Set parameter p2051[5] = r0037[3] (Air intake temperature to PZD 6).
- Copy RAM to ROM in the drive to save parameter changes permanently.
Interconnect Driver Block in CFC:
- In CFC, open the chart with the APL_G120 (or FbDrive) block.
- Insert two MonAnL blocks from the PCS 7 Advanced Process Library.
- Interconnect APL_G120.PCD5Out to MonAnL_1.PV_In.Value (with type conversion or scaling if temperature is in fixed-point format).
- Set the engineering unit parameter MonAnL_1.PV_InUnit = 1001 ($^\circ\text{C}$).
- Set alarm limits: AH_Lim = 85.0 $^\circ\text{C}$, WH_Lim = 75.0 $^\circ\text{C}$.
Compile and Download:
- Compile CFC charts and download to the AS controller.
- Compile the OS: position the newly generated MonAnL block icons on the WinCC motor overview graphic.

Verification

Verify temperature acquisition through the following checks:
1. In STARTER online parameter view, check r0037[0]: record the physical temperature (e.g., $48.5^\circ\text{C}$).
2. In CFC online test mode, inspect MonAnL_1.PV_Out.Value: confirm that the live value matches the drive display.
3. On the WinCC OS client, open the MonAnL faceplate: confirm that the bar graph, live value, and engineering unit display correctly.
4. In WinCC TrendControl, open a trend window: verify that inverter temperature traces continuously alongside motor speed and current.

Limitations and Operational Precautions

When mapping temperature parameters to cyclic telegram words, verify the numeric scaling of the drive parameter. Some SINAMICS parameters transmit raw 16-bit integer values in degrees Celsius, while others scale values relative to reference temperature p2006 (where 16#4000 hex represents 100% of reference temperature). Failure to verify scaling will result in distorted temperature readouts. Always cross-check the drive parameter manual before setting alarm limits.

Engineer FAQ

What is the difference between Telegram 1 and Telegram 352 on SINAMICS?

Telegram 1 transmits 2 words In / 2 words Out (Speed and Control/Status). Telegram 352 transmits 6 words In / 2 words Out, providing 4 additional feedback words for current, torque, fault codes, or custom BICO variables.

Can I read motor winding temperatures (PT100 / PTC) using this same method?

Yes. If the motor is equipped with temperature sensors connected to the G120 (terminals or Sensor Module), map parameter r0035 (motor temperature) to a free PZD word in p2051.