Configuring S7-1500 PROFINET Telegram 370 for SINAMICS S120

Overview: S7-1500 to SINAMICS S120 CU320-2 PN PROFINET Architecture

The SIMATIC S7-1500 CPU communicates with a SINAMICS S120 drive line-up over PROFINET IO using the CU320-2 PN control unit as the PROFINET IO Device. Communication is telegraphic: the controller sends a Process Data (PZD) set (control words, setpoints) and receives a PZD set (status words, actual values) in each PROFINET IRT/RT cycle. For infeed units (Line Module, Basic Line Module, Smart Line Module, Active Line Module) and additional drive objects beyond the standard drive telegrams, Siemens provides supplementary telegrams such as Telegram 370 for the Infeed and Telegram 390 for the Control Unit, while axis telegrams 1, 2, 3, 4, 5, 6, 7, 9, 20, 110, 111, 116, 118, 125, 126, 130, 136, 138, 139, 166, 220, 222 handle servo and vector control.

This article documents the field-proven procedure to bring up Telegram 370 (PZD 1/1) on a CU320-2 PN so that the S7-1500 can request Master Control by PLC (Bit 10 of Control Word 1, STW1) and switch the infeed on and off. The procedure applies whether the S7-1500 is a separate PLC next to the drive line-up, or integrated into the same device as in a SIMATIC Drive Controller (a fused S7-1500 Technology CPU and SINAMICS S120 Booksize Compact in one chassis). See the SIMATIC Drive Controller product overview in the TIA Portal manual collection for the integrated variant.

Prerequisites and Required Firmware Versions

Before commissioning, confirm the following minimum firmware and software versions. Field experience shows that older SINAMICS S120 firmware rejects Telegram 370 activation by the PLC, even if STARTER or Startdrive accepts the configuration silently.

Telegram 370 Structure and PZD Mapping for Infeed

Telegram 370 carries a single Process Data word in each direction for the infeed control object (DO Infeed). The mapping follows the PROFIdrive profile v4.1:

The PLC must set Bit 10 (Master Control by PLC) of STW1 to 1 for the drive to accept any other control bits. If Bit 10 is 0, the drive ignores ON commands and reports back ZSW1 Bit 10 = 0. This is the most common root cause for "Drive does not switch on" complaints - the field has many cases where commissioning engineers set ON/OFF but forget Master Control.

HW Configuration in TIA Portal: Identifying the HW Identifier

Telegram 370 appears in the device view of the CU320-2 PN as a dedicated submodule slot once the GSDML/HSP is installed. The critical step is to read the correct Hardware Identifier (HW ID) that the S7-1500 program will use as the LADDR input to DPWR_DAT / DPRD_DAT.

1. Open the project in TIA Portal and switch to Device view.
2. Select the CU320-2 PN node in the PROFINET network.
3. Open Device overview > Telegram configuration. Telegram 370 should now appear under the Infeed slot (usually slot 2 or 3, depending on DO assignment).
4. Note the I/O addresses assigned to Telegram 370: input start address (e.g., I 300) and output start address (e.g., Q 300).
5. Right-click the Telegram 370 submodule → Properties > System constants. The HW ID is shown here as a hexadecimal value (for example, 272 decimal or 0110 hex) and is the value to load into the DPWR_DAT/DPRD_DAT LADDR parameter.

PROFINET Telegram Slot Assignment and I/O Address Mapping

The CU320-2 PN exposes telegram slots in this typical order (depends on the DO list):

The I/O addresses shown are user-configurable in Device view > Telegram > I/O addresses. For most applications, the default packed addressing is fine. Avoid leaving gaps that double the PROFINET frame - S120 is sensitive to frame length settings beyond what STARTER reports.

Writing the Control Word with DPWR_DAT on S7-1500

On S7-300/400, SFC14 (DPRD_DAT) and SFC15 (DPWR_DAT) read and write consistent PROFINET data. On S7-1500, the equivalent instructions are the integrated DPWR_DAT and DPRD_DAT blocks available from the Instructions > Communication > PROFINET IO palette in TIA Portal. They behave identically to SFC14/15 but use the new LAD/FBD block icon and support symbolic naming.

Example ST code for switching the infeed on:

// DB100 "Infeed_Ctrl" - contains STW1 and ZSW1
// DB100.DBX0.0  WORD  Infeed_STW1   // Setpoint to drive
// DB110.DBX0.0  WORD  Infeed_ZSW1   // Actual from drive

// Build control word: Bit 0 = ON, Bit 10 = Master Control by PLC, Bit 14 = Command Setpoint
#Infeed_STW1 := 16#0000;
#Infeed_STW1 := #Infeed_STW1 OR 16#0001;  // Bit 0 - ON/OFF1
#Infeed_STW1 := #Infeed_STW1 OR 16#0400;  // Bit 10 - Master Control by PLC
// Bit 14 toggled each cycle for Command Setpoint; handled in OB1 by a flip-flop

DPRD_DAT(LADDR := 272,                // HW ID of Telegram 370
         RET_VAL := #ret_read,
         RECORD := P#DB110.DBX0.0 WORD 1);

DPWR_DAT(LADDR := 272,                // HW ID of Telegram 370
         RECORD := P#DB100.DBX0.0 WORD 1);

If the Any pointer in RECORD points to a data block (DB), TIA Portal V14+ accepts it directly - unlike the older SFC14/15 where the DB had to be unoptimized. With S7-1500 optimized DBs, ensure Accessible from S7-300/400 is unchecked (or use Standard access) and that the address area is word-aligned.

PUTIO and GETIO as an Alternative

The PUTIO and GETIO instructions transfer the entire I/O image of a PROFINET device in one call. They are useful for diagnostic or development phases where you want to mirror all telegram data without per-telegram block calls. Field experience shows PUTIO/GETIO often returns no error but does not change drive data when the wrong HW ID is loaded - this matches the symptom reported in the original question.

// Read all submodules of CU320-2 PN into DB200
GETIO(MODE       := 1,            // 0 = read all, 1 = read partial
      LADDR      := 256,          // HW ID of the CU320-2 PN device (head station)
      RET_VAL    := #ret_io,
      BUSY       := #busy_io,
      RECORD     := P#DB200.DBX0.0 BYTE 256);

For production code, prefer DPWR_DAT/DPRD_DAT per telegram. The PUTIO/GETIO approach makes the cyclic I/O update depend on a single scan, which can interfere with isochronous applications.

Word/Byte Swapping and SINAMICS S120 Data Inversion

PROFINET telegrams on Siemens drives transfer PZD words in big-endian byte order. The S7-1500 stores words little-endian. A single-word PZD (Telegram 370 case) does not exhibit visible byte-swap effects because both bytes are part of the same 16-bit word and the swap preserves the word value. However, for multi-word PZD sets (Telegram 220, Telegram 5, Telegram 136, etc.) the order of the words in the data block must be reversed unless the swap is handled by the CPU's PROFINET stack.

For a single-word Telegram 370, the canonical safe pattern is to treat the value as a word and avoid manual bit-level reordering. Use the word symbol Infeed_STW1 and set bits via the OR mask shown in the ST example above.

PLC Master Control Request Sequencing

The PROFIdrive state machine for an infeed is simpler than a motor drive. The required sequence in STW1 is:

1. Bit 10 = 1 (Master Control by PLC) - always required to give the PLC authority.
2. Bit 0 = 1 (ON/OFF1) - close the main contactor / pre-charge.
3. Wait for ZSW1 Bit 2 = 1 (Operation Enabled) and ZSW1 Bit 10 = 1 (Master Control echoed back).
4. For shutdown: Bit 0 = 0 (OFF1, controlled ramp-down) or Bit 1 = 0 (OFF2, immediate pulse inhibit).

A common fault pattern: the S7-1500 sets Bit 0 = 1 but the drive stays in Switch-on Inhibited (ZSW1 Bit 6 = 1) because Bit 10 was never set. This produces a perfectly valid STW1 from the PLC side but no reaction on the drive side, and STARTER will report "Missing Master Control by PLC" in the control panel diagnostic buffer.

Commissioning Procedure with STARTER or Startdrive

1. In STARTER/Startdrive, navigate to the CU320-2 PN and add Telegram 370 to the Infeed DO.
2. Download the project to the drive and perform a POWER ON (POW) reset so the new telegram configuration is active.
3. Open Control panel in STARTER; the Master control by PLC checkbox should be present for the infeed.
4. Tick the checkbox manually to verify the drive reacts (infeed contactor closes, DC link charges).
5. Untick the checkbox, then switch to online monitoring of the S7-1500.
6. Trigger DPWR_DAT from the S7-1500 with Bit 10 = 1 and Bit 0 = 1. The drive should now show "Control by PLC" and switch on.
7. Use the drive trace to record ZSW1 and confirm Bit 2 toggles to 1.

Verification Checklist

Troubleshooting Matrix

References to Official Documentation

The procedure above is documented in detail in the SINAMICS S120 Commissioning Manual and the Function Manual "Communication" in the Siemens support documentation system. The classic application note that consolidates the PLC-to-drive PROFINET pattern with DPWR_DAT/DPRD_DAT is entry ID 73257075 in the Siemens Industry Online Support; a related FAQ for telegram 220 with DPWR_DAT/DPWR_DAT is entry ID 82887493. Both are listed under Function Manuals > SINAMICS S120 > Communication (PROFINET/PROFIdrive). The integrated SIMATIC Drive Controller variant - which combines an S7-1500 Technology CPU and an S120 Booksize Compact in one enclosure - is described in the TIA Portal manual collection for S7-1500 / ET 200 MP.

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