Accessing SINAMICS G120 Onboard AI and DI in TIA Portal

1. Overview of the SINAMICS G120 Onboard I/O Architecture

The SINAMICS G120 modular drive system consists of two main hardware blocks: a Power Module (PM) that contains the rectifier and inverter, and a Control Unit (CU) that handles communication, closed-loop control, and signal I/O. The CU is the part that exposes the PROFINET interface, the onboard digital inputs (DI), digital outputs (DO), analog inputs (AI), and analog outputs (AO). When a user inserts a G120 PN drive from the TIA Portal hardware catalog, the GSDML describes the drive as a single PROFINET device with a limited set of slots and submodules. This is why the onboard CU I/O does not appear as "AI/AO submodule" the way it does for an ET 200MP AI module: the AI/DI live inside the drive, and you reach them through process data words (PZD) inside a PROFINET telegram, not through discrete I/O slots.

To read a 4-20 mA sensor wired to the CU screw terminals as an Int tag inside the S7-1500 user program, you must:

1. Configure the AI signal type and scaling in the CU (via Startdrive or STARTER).
2. Add a PZD word to the cyclic PROFINET telegram that carries the AI actual value to the PLC.
3. Assign a tag name to the input PZD word in the PLC tag table.

2. Identifying the Control Unit and Onboard I/O Specification

The drive in the source example has the MLFB 6SL3210-1KE24-4UF1, which is a PM240-2 Power Module (22 kW, 400 V class) combined with a CU240E-2 PN Control Unit. The "PN" suffix indicates PROFINET as the fieldbus, and the "E" in 240E indicates the Extended I/O variant. The CU240E-2 PN is documented in the SINAMICS G120 Operating Instructions and provides the following onboard I/O:

The two analog inputs are differential inputs with 12-bit resolution and a 0.1 ms conversion time. AI 0 supports voltage, current, and temperature modes; AI 1 supports voltage and current. For a 4-20 mA sensor signal, configure AI 0 in current mode.

3. PROFINET Telegrams and PZD Payload Structure

SINAMICS drives exchange real-time data with the S7 controller over PROFINET using cyclic PZD telegrams. Each telegram is a fixed-length payload containing 16-bit words:

• Receive PZD (PLC → drive): control word (STW), speed setpoint (NSOLL), torque limit, ramp times, etc.
• Send PZD (drive → PLC): status word (ZSW), speed actual (NIST), current, fault code, and — the key point — any SINAMICS connector (r-parameter) that you interconnect to a PZD slot.

Common standard telegrams supported by the G120 are listed below. The number of PZD words directly determines how many 16-bit tags the PLC can read from the drive per cycle.

The "free" or "SIEMENS 35x" telegrams are the only paths that allow you to assign the AI actual value to a specific PZD word. Telegram 1 cannot be modified.

4. Hardware Configuration in TIA Portal V17

4.1 Prerequisites

• TIA Portal V17 with Startdrive V17 installed.
• SINAMICS G120 GSDML-V2.35-Siemens-Sinamics-S120-… (or the Startdrive device library entry).
• CPU firmware ≥ 2.9 (S7-1500) or 4.4 (S7-1200) — required for free telegram support.
• Drive firmware matching Startdrive V17 SP1 (CU240E-2 PN V4.7 SP10 or later recommended).

4.2 Step-by-step device insertion

1. Open the project in TIA Portal V17 and switch to the Device & Networks view.
2. From the hardware catalog, navigate to Drives & Starter Kits → SINAMICS Drives → SINAMICS G120 PN. Use the Startdrive version of the device (not the legacy HSP/GSD), so the drive is commissioned directly from TIA Portal.
3. Drag the G120 PN onto the PROFINET subnet. Assign the same IO controller as the S7-1500.
4. Click the G120 and open Properties → Telegram configuration. By default, TIA Portal inserts Standard Telegram 1 on IF1 (PROFINET).
5. Click Add telegram and select SIEMENS Telegram 352 (or 354). Telegram 352 provides 6 PZD words each direction, which leaves room for control + status + 4 free words.
6. Optionally remove Telegram 1 if you do not need the speed profile; you can keep both, in which case the PLC sees two IO areas.
7. Compile the hardware configuration. The PLC now has an IO area in the format IW x...x for receive PZD and QW x...x for send PZD. TIA Portal automatically places these in the process image; note the start address in the device overview.

5. Mapping AI 0 and DI 0 to PZD via Free Telegram Configuration

Defining the telegram in TIA Portal only reserves a slot; you must still wire the slot to a real SINAMICS signal. This is done in the Parameter view of the drive (Startdrive) or online in Online & Diagnostics. The relevant parameters are p2051 for IF1 send-PZD interconnection and p2061 for receive-PZD.

5.1 Parameter mapping for AI 0 → PZD out word 3

Note: r0755[0] returns a normalized value with the scaling defined by p0757/p0758/p0759/p0760. By default the AI is bipolar ±10 V scaled to ±100% = ±16384. For a 4-20 mA unipolar loop you must re-scale the AI as shown in §5.3.

5.2 Parameter mapping for DI 0..5 status

SINAMICS provides r0722 as a bit-coded status of all digital inputs. To get the complete DI word into one PZD slot, use bit-to-word conversion. The simplest approach is to interconnect the connector r0722 directly to p2051[n]; the drive packs the bits into the low byte of the word.

• Bit 0 = DI 0, Bit 1 = DI 1, … Bit 5 = DI 5
• Bits 8-15 = DO 0-2 status (DO feedback via r0747) — also packed

If you only need a single DI, mask it in the PLC rather than consuming a whole PZD word.

5.3 Required AI 0 scaling for a 4-20 mA sensor

1. Set p0756[0] = 2 — current input, unipolar, 4-20 mA, monitoring enabled.
2. Set p0757[0] = 4.0 — x1 of the linear characteristic (mA).
3. Set p0758[0] = 0 — y1 of the linear characteristic (output percent).
4. Set p0759[0] = 20.0 — x2 of the linear characteristic (mA).
5. Set p0760[0] = 100 — y2 of the linear characteristic (output percent).
6. Set p0761[0] = 4 — wire-break threshold equals 4 mA, the loop low end.
7. Optional: set p0755[0] smoothing via p0753[0] = 10 (10 ms filter).

With the above, the connector r0755[0] outputs a normalized percentage from 0 to 100, with 4 mA giving 0% and 20 mA giving 100%. When the drive places this in a PZD word, the PLC receives an integer where 0 = 4 mA and 16384 = 100% = 20 mA. The scaling factor is 163.84 per mA above 4 mA.

6. Reading the AI Value in the PLC Program

After the telegram is configured and downloaded, the S7-1500 device view shows the input PZD area. In the example, with Telegram 352 starting at IB 100, the layout is:

The simplest scaling from raw integer to engineering units (e.g., pressure in bar) is done in SCL:

// FB_Sensor_Scale
FUNCTION_BLOCK "FB_Sensor_Scale"
VAR_INPUT
    RawInput : INT;        // 0..16384 corresponds to 4..20 mA
    EngMin   : REAL;       // e.g. 0.0   (bar at 4 mA)
    EngMax   : REAL;       // e.g. 10.0  (bar at 20 mA)
END_VAR
VAR_OUTPUT
    EngValue : REAL;
    bFault   : BOOL;       // TRUE if wire break / underrange
END_VAR
VAR
    Percent  : REAL;
END_VAR
BEGIN
    IF RawInput < 0 THEN
        // Wire break or AI fault reported by SINAMICS
        bFault   := TRUE;
        EngValue := 0.0;
    ELSE
        bFault   := FALSE;
        Percent  := INT_TO_REAL(RawInput) / 163.84;  // % above 4 mA
        // Limit to 0..100 %
        IF Percent < 0.0   THEN Percent := 0.0;   END_IF;
        IF Percent > 100.0 THEN Percent := 100.0; END_IF;
        EngValue := EngMin + (Percent / 100.0) * (EngMax - EngMin);
    END_IF;
END_FUNCTION_BLOCK

Call the FB in the cyclic OB1 with Sensor1_Raw as input:

"Inst_Sensor1"(RawInput := "DB_Drive".Sensor1_Raw,
               EngMin   := 0.0,
               EngMax   := 10.0,
               EngValue => Pressure1_bar,
               bFault   => Sensor1_Fault);

7. Commissioning with Startdrive

1. In the project tree, right-click the SINAMICS G120 PN → Commissioning. Startdrive opens an online connection to the drive via PROFINET.
2. Open Parameter view and filter by p0756, p0757, p0758, p0759, p0760, p0761. Apply the values from §5.3.
3. Filter by p2051 and verify the send-PZD interconnections; in Telegram 352, the default map may already match the standard profile, but free words 2, 3, 4, 5 must be edited. Type the parameter number (e.g., 755[0]) directly into the Signal source field.
4. Click RAM → ROM (or Copy RAM to ROM) to persist the parameter changes into the CF card of the CU.
5. Click Download in the device view to push the telegram configuration to the S7-1500.
6. Cycle power on the drive (or run Commissioning → Commissioning wizard) to activate the new telegram mapping.

8. Verification and Diagnostics

8.1 Functional check

1. Force a 12 mA test signal at AI 0. The expected PZD value is:

   Percent = (12 - 4) / (20 - 4) * 100 = 50 %
   Raw_PZD = 50 % * 163.84 = 8192 (0x2000)

2. Open a watch table in TIA Portal online view on the input PZD area. IW 104 should display 8192 (±1 LSB).
3. Open the SINAMICS online diagnostics (Startdrive → Diagnostics → Status words). r0755[0] should display 50.0 %.

8.2 PROFINET diagnostics

• F08501 — PROFINET communication fault. Cause: telegram changed but PLC not recompiled.
• F08502 — Sign-of-life timeout. Cause: bus cycle > configured watch-dog (p2047).
• F08510 — Send-PZD configuration error. Cause: p2051 index points to a non-existent connector.
• A08511 — Receive-PZD configuration error. Cause: p2061 points to a non-interconnectable binector.

Detailed fault codes are in the SINAMICS G120/S120 List Manual (function diagrams 2410, 2420, 2423).

9. Troubleshooting Matrix

10. Alternate Approaches and Field Notes

If the drive's onboard AI/DI is genuinely insufficient (e.g., the user needs fast 24-bit AI for a load cell), Siemens recommends installing a separate PROFINET I/O device such as an ET 200SP AI 8xRTD/TC (6ES7534-7QE00-0AB0) or ET 200MP AI 8xU/I/RTD (6ES7531-7KF00-0AB0). The drive's onboard AI is intended for slow process signals (0-10 V, 0/4-20 mA) with 12-bit resolution, not for precision measurement.

For safety-related DI (e.g., STO via PROFIsafe), the user must use a CU240E-2 FS variant (e.g., 6SL3210-1KE24-4AF1) and configure PROFIsafe slots in TIA Portal, not the onboard DI; the FS DI is wired to the F-DI block on PROFINET slot 1. Standard onboard DI 0-3 are not safety-rated.

When commissioning multiple G120 PN drives, the free-telegram pattern is identical: assign a unique PROFINET device name, configure the same Telegram 352, and copy the same parameter set from a master drive using Startdrive's Compare & Parameterize function. The parameter snapshot can be exported as a *.par file and pushed to each new drive, ensuring uniform behavior across a fleet of agitators or pumps.