SINAMICS G120 Fault Code Read via SINA_SPEED and S7-1500

Problem Overview

An S7-1500 controller drives a SINAMICS G120 (CU240E-2 PN, CU250S-2 PN, or later) over PROFINET using the SINA_SPEED function block from the Siemens SINAMICS blocks library. The control program is built on Standard Telegram 1 (PZD-4/4: STW1 + NSOLL out, ZSW1 + NIST in) and the existing project must stay on that telegram. When a drive fault occurs, the PLC must still read the SINAMICS fault number and present it on the HMI / SCADA.

The challenge: Telegram 1 does not carry the fault code in cyclic data. Only the status word bit "Fault present" is visible cyclically. The actual fault number (r945, r947, r2131) must be fetched with an acyclic read, or the user must switch to a Siemens-specific telegram that includes the fault code word.

This reference covers both paths: keep Telegram 1 and use SINA_PARA (acyclic DPV1 read) on the PLC side, or switch to Telegram 352 which exposes the current fault number in the cyclic process data.

Telegram 1 vs. Telegram 352 Layout

The selection of the PROFINET telegram determines which process data the drive exposes in real time. Telegram 1 is the lean, vendor-neutral layout; Telegram 352 is a Siemens-specific, G120-optimized layout that includes extra control bits and a fault-code word.

With Telegram 352, PZD4 IN carries the active SINAMICS fault number directly to the PLC on every bus cycle. With Telegram 1, the PLC sees the bit ZSW1.3 = "Fault present" but no fault code, and must poll the drive over the acyclic channel.

Status Word 1 (ZSW1) Fault and Warning Bits

These are the ZSW1 bits the PLC evaluates cyclically regardless of which telegram is in use. All bit numbering is Siemens convention, bit 0 = LSB.

Recommended PLC logic: monitor ZSW1.3 on every cycle. On a rising edge, latch the fault-present flag and trigger the acyclic SINA_PARA read. On a falling edge (acknowledge / clear), clear the latched flag and the last fault number.

SINA_SPEED Interface (FB285) on S7-1500

The SINA_SPEED function block is the standard Siemens interface for cyclic speed control of a SINAMICS G/S/V drive. For an S7-1500 it is loaded from the global SINAMICS blocks library, declared as a multi-instance inside the user FB, or instantiated as DB. The block handles the conversion between the speed setpoint (RPM, real) and the N2 format the drive expects, the control word bit assembly, and the lifecycle of the axis state machine.

The SINA_SPEED instance does not surface the SINAMICS fault number on its own. The block only returns AxisFaulted (mirroring ZSW1.3). To get the fault number, the user program must either (a) read an acyclic parameter with SINA_PARA, or (b) extract the fault number from Telegram 352's PZD4 IN.

SINA_PARA Acyclic Read (FB286) Procedure

SINA_PARA performs an acyclic DPV1 read/write of a single SINAMICS parameter. With Telegram 1 in use, this is the standard path to read r945, r947, r0947, r2131, r0949[0], or the full fault buffer.

Key parameters to read on a SINAMICS G120:

TIA Portal Configuration Steps

1. Add drive to device configuration. Open the S7-1500 project in TIA Portal. Drag the SINAMICS G120 from the hardware catalog (e.g. SIMATIC S7-1500 → Drives → SINAMICS G120 → CU240E-2 PN F) into the PROFINET network. Connect it to the S7-1500 PN interface.
2. Assign the PROFINET device name. Use Online → Accessible devices → Assign PROFINET device name. The PLC must be able to AR (Application Relationship) the drive before the cyclic data is exchanged.
3. Insert the telegram. In the drive's Properties → Device view → Telegram configuration, set Standard Telegram 1, PZD-4/4. Note the hardware identifier of the IO device — you will assign it to the HwInputOutput input of SINA_SPEED and SINA_PARA.
4. Add the SINAMICS blocks library. Libraries → Global libraries → SINAMICS blocks. Drag SINA_SPEED (FB285) and SINA_PARA (FB286) into your program. For an S7-1500 the latest version is required (V4.0 or higher for the G120 multi-instance usage).
5. Call SINA_SPEED in OB1 / cyclic OB. Use a rising-edge detector on ZSW1.3 from the same drive's input PZD to drive the fault-handling state machine.
6. Call SINA_PARA in a time-controlled OB (e.g. OB30 / OB35 at 100 ms) so that the acyclic request does not block the cyclic exchange. Only trigger the SINA_PARA when the fault bit is latched.
7. Map the parameter to HMI. Export the read DINT to a tag on the HMI (e.g. DB_Common.G120_FaultCode) and use it on a fault message view.

Structured Text Example: SINA_SPEED + SINA_PARA

The following SCL (Structured Control Language) snippet illustrates a complete axis block for a G120 with Telegram 1 and acyclic fault readout. The block is called from OB1 (cyclic, 4 ms) and from OB35 (100 ms) for the acyclic read.

// --- Cyclic call (OB1, 4 ms) ---
IF bEnable THEN
  iSinaSpeed(EnableAxis := bEnable,
             AckError   := bAckPushbutton,
             SpeedSetpoint := rSetpointRPM,
             ConfigAxis := dwConfig,
             RefSpeed   := 1500.0,
             HwInputOutput := hwG120,
             AxisEnabled => bAxisEnabled,
             AxisFaulted => bAxisFaulted,
             AxisWarn    => bAxisWarn,
             ActSpeed    => rActualRPM,
             ActCurrent  => rActualCurrent,
             Error       => bFbError,
             Status      => wFbStatus);
END_IF;

// Latch the fault-present edge
IF bAxisFaulted AND NOT bFaultLatched THEN
  bFaultLatched := TRUE;
  bReadNow      := TRUE;          // trigger acyclic SINA_PARA
  iReadBusy    := FALSE;
END_IF;

IF NOT bAxisFaulted AND bFaultLatched THEN
  bFaultLatched := FALSE;
  dwFaultCode   := 0;
END_IF;

// --- 100 ms call (OB35) ---
// One SINA_PARA read of r0947. Re-trigger on Done or Error.
IF bReadNow AND NOT iSinaPara.Busy THEN
  iSinaPara(Request         := bReadNow,
            ReadWrite        := FALSE,
            ParameterNumber  := 947,         // r0947 fault number, current
            Index            := 0,
            ValueDINT        := 0,
            HwInputOutput    := hwG120,
            Done             => bReadDone,
            Busy             => bReadBusy,
            Error            => bReadError,
            ErrorNum         => wReadErrNum,
            ValueReadDINT    => dwFaultCode);
  bReadNow := FALSE;               // single-shot
END_IF;

Use dwFaultCode in the HMI. For a human-readable description, copy the SINAMICS list of fault codes (function manual Firmware Version V5.2 / V6.4, depending on the CU) into the HMI text list.

Alternative Path: Telegram 352 with Cyclic Fault Number

If the communication overhead is acceptable (only 2 extra PZD per direction), switch to Telegram 352. The PLC will receive the active fault number on every bus cycle on PZD4 IN. SINA_PARA is no longer required for fault-number retrieval, but is still useful for reading the diagnostic buffer (r0949[0..63]) and warnings (r2110).

Telegram 352 also adds ZSW3 (status word 3) and STW3 (control word 3) which carry the additional control bits the G120 supports, e.g. motor identification, fixed setpoints, etc. If your existing project had a custom FB that read STW3 / ZSW3 manually, you can either extend SINA_SPEED with the LSINAExt example, or read ZSW3 directly from the input PZD area.

Verification and Commissioning

1. Bring drive to fault intentionally. In Startdrive, force a fault: set p0009 = 1 to enter commissioning, then trigger a "simulated fault" (e.g. trip encoder loss by setting p0400 = 0 on a closed-loop FVC configuration, then restore). Acknowledge and re-try the procedure.
2. Watch ZSW1.3 in the watch table. Open a watch table on the axis DB and monitor AxisFaulted. It must go TRUE the cycle after the fault is set.
3. Watch the acyclic SINA_PARA response. In the same watch table, monitor dwFaultCode, bReadDone, bReadError, wReadErrNum. After the latched edge the value must appear within the OB35 cycle (100 ms).
4. Cross-check with Startdrive online. In Startdrive → Online → Diagnostics buffer, confirm the r947 number matches the PLC's dwFaultCode. The values must be byte-identical.
5. Test the acknowledge chain. With the fault still active in the drive, press the HMI's "Ack" button → PLC sets AckError := TRUE → ZSW1.3 falls → bFaultLatched := FALSE. The drive must be ready to run again after the next ON command.
6. Test the cyclic path (if Telegram 352). If Telegram 352 is in use, force a fault and read PZD4 IN from the I/O start address. The value must match the diagnostic buffer without any acyclic request.

Troubleshooting Matrix

Field-Proven Caveats

• One SINA_PARA at a time per drive. The SINA_PARA block is single-instance per request. Trigger a new request only after Done OR Error has fired; otherwise the second trigger is lost on a busy state machine.
• Index of r0947 and r0949. r0947 is indexed but only r0947[0] is the "current" fault. The other indices are the history. Read Index = 0.
• Type matching. Use ValueDINT for r0947, r0949, r2131 (32-bit signed). Using the REAL input returns garbage on integer parameters and vice-versa.
• OB1 vs OB35 cycle time. Acyclic parameter requests are sequential; if the SINA_PARA is called in the 4 ms OB1 the drive-side response time (~10–50 ms typical) can stall the SINA_PARA state machine. Call the block from a 50–100 ms time-controlled OB.
• Read-only buffer reset on power cycle. The diagnostic buffer (r0949, r2135) is in volatile memory by default. To retain it across mains-off, write p0964 = 0 to disable the power-up reset of the diagnostic buffer (firmware-dependent).
• CPU firmware compatibility. On the S7-1500, the SINA_SPEED block requires at least TIA Portal V16 + SINAMICS blocks library V4.0. For the S7-1200 the same FB is used; the application example is titled for the S7-1200 (entry ID 109485727) but applies identically to the S7-1500.

FAQ