Stop a Simovert Masterdrive Motor in Auto Mode While Other Drives Keep Running

1. Problem Definition and Engineering Goal

On a multi-section conveyor the supervisory controller (PLC or DCS) runs the line in Auto mode. A fault, scheduled maintenance, or a process diversion requirement demands that one drive be stopped while the others continue to run at their last valid setpoint. The challenge is to implement the stop deterministically through the SIMOVERT MASTERDRIVES command interface rather than by removing enable voltage or by opening a contactor, which would trip an undervoltage fault on the inverter.

Engineering goals for a correct implementation:

• Issue a controlled ramp-down (OFF1) to the affected drive, not a coast-down (OFF2) or fast stop (OFF3), unless specifically required.
• Keep the inverter powered and in Ready state so the drive can be re-enabled without a full power cycle.
• Allow the other drives to maintain speed and torque reference unchanged.
• Provide a fault-acknowledge path so the same drive can be re-energized when the condition clears.

2. SIMOVERT MASTERDRIVES Control Architecture Overview

The SIMOVERT MASTERDRIVES family (compact units 6SE7011–6SE7090, chassis units 6SE7101–6SE7188, and the VC and MC control boards) is built on a three-tier signal model documented in the SIMOVERT MASTERDRIVES Vector Control manual (VC332):

1. Binectors – digital (boolean) signals identified by a B-prefix, e.g. B0000, B0020, B0100. They are the binary equivalents of wires in a hardwired panel.
2. Connectors – 16-bit or 32-bit numeric signals identified by a K-prefix, e.g. K0001 (setpoint), K0033 (status word). They are the equivalents of analogue wires and fieldbus process data words.
3. BICO technology – the parameter system that lets you re-wire any binector to any control input and any connector to any setpoint input. Every control and setpoint source is a parameter (P554…P590) that points to a BICO source.

To stop a single drive in Auto you do not remove any wiring. You re-target the OFF command (control word bit 0 for OFF1, bit 1 for OFF2) through BICO so that the PLC, a free-function block, or a terminal input can clear it without affecting neighbouring drives.

3. Control Word 1 Bit Structure and OFF Commands

Control Word 1 (STW1, K0030) is the primary 16-bit command interface to the drive. The bits used for the most common stop commands are:

4. Auto Mode Command Source – Where the Stop Comes From

The Auto mode question always reduces to one engineering question: which binector is the source of STW1 bit 0? The parameter that answers this is P554 (source of Control Word 1, bit 0). Default values for the standard configuration are:

The binector numbers B2700–B2715 are the fieldbus-decoded bits of the first 16-bit process-output word. The PLC toggles the appropriate bit in the cyclic output image and the inverter receives an ON, OFF, or fault-acknowledge command without any wiring change.

5. BICO Wiring of a Selective Auto-Stop

To stop one drive on a line of several drives, the PLC writes a unique bit per drive into the process-data image. The pattern uses the Bit 0 (ON/OFF1) of the per-drive control word. The implementation sequence in DriveMonitor / Simovert commissioning software:

1. Connect to the target drive via serial (RS232 adapter) or PROFIBUS.
2. Open the parameter tree and navigate to P554.0.
3. Confirm the source is the fieldbus bit that your PLC toggles for that drive, e.g. B2700.
4. Set P590 so that Auto mode is selected by the fieldbus bit, not by a terminal (P590 = 0 for a free-function-block output, P590 = 5000 for terminal).
5. Save to the EEPROM (P052 = 1 + run the save routine, or use DriveMonitor » » save in non-volatile memory).

6. Free Function Blocks (FFB) for Logic Combining

Where the stop decision involves more than a single digital input (e.g. stop this drive if main-line drive is faulted AND side-leg is in divert position AND manual override is off), use the FFBs of the CU board:

The FFB output is itself a binector. Re-wire P554.0 to point at the FFB output and the OFF1 command will be issued when the FFB condition evaluates to 0.

7. PLC and DCS Integration

From a SIMATIC S7-300 / S7-400 (or any PROFIBUS-DP master) the control word is written as the first two output bytes of the assigned slot. Example of the S7 data block layout for one drive:

DATA_BLOCK DB 20   // Per-drive command block (offset = drive number x 4)
  STRUCT
    STW1   : WORD;    // Control word 1, bits per Section 3
    NSOLL  : INT;     // Speed setpoint (N_SET, in 0x4000 + scaling)
    STW2   : WORD;    // Control word 2 (optional, depends on P587)
    // Bits in STW1 for this application:
    //   .0  ON/OFF1    1 = run, 0 = ramp to stop
    //   .3  Enable     1 = inverter enabled
    //   .7  Ack        0 -> 1 rising edge = fault reset
    //   .10 Control by PLC = 1 (required for B2700 decoding)
  END_STRUCT
END_DATA_BLOCK

At the PLC side, the line control program toggles STW1.0 for the affected drive. Drive N remains unaffected because its control word is a different slot/word. Typical S7 code in FBD:

// Section 1: collect stop requests
   "Tag_Stop_1"  := "iDrive1_Trip" OR "iMaint_1" OR "iSideLeg_Full";
   "Tag_Stop_2"  := "iDrive2_Trip" OR "iMaint_2";

// Section 2: clear ON/OFF1 bit on the affected drive only
   DB20["Drive_1"].STW1.%X0 := NOT "Tag_Stop_1";  // bit 0
   DB20["Drive_2"].STW1.%X0 := NOT "Tag_Stop_2";  // bit 0
   // All other drives: STW1.%X0 := TRUE; // keep them running

For USS-protocol drives the same logic applies, but the control word is byte 0 of the PKW/PZD telegram rather than PROFIBUS PPO. In DriveMonitor the source binector for USS is in the B0100…B0115 range.

8. Servo Motor 1FK7100-5AF71-1TG0 Specifics

The motor 1FK7100-5AF71-1TG0 is a SIMOTICS 1FK7 high-inertia servo motor with the following relevant data, all of which must be loaded into P115 motor-identification before the drive will accept a controlled OFF1 ramp:

For a 1FK7 motor the OFF1 ramp is normally set very short (P464 = 1.0 s to 3.0 s) because the load is usually a low-inertia conveyor section; verify that the mechanical coupling can absorb the deceleration torque, otherwise use OFF3 with a longer P466 value to avoid belt slip.

9. Conveyor Line Application Example – Float Glass Cold End

Topology of the described application:

Operating scenarios implemented entirely through the BICO command path:

1. M1 trips, glass must divert to M2: PLC sets STW1.0 = 0 for M1 (OFF1 ramp) and keeps STW1.0 = 1 for M2 and M3. The glass sheet is now routed by the divert mechanism into the side-leg section.
2. M2 needs to stop after the divert cycle ends: Once the side-leg position sensor B10003 = 1, the PLC clears STW1.0 for M2. M3 remains on, M1 stays off.
3. Reset: M1 is repaired. PLC pulses STW1.7 (0→1→0) on M1 to clear fault F008 / F015 / F030, then raises STW1.0 = 1 to bring it back on-line. The line returns to full automatic run.

10. Verification and Commissioning Procedure

After wiring the BICO sources and writing the PLC code, perform the following checks before running production:

1. Read r000 on the PMU / DriveMonitor. Inverter should be in state o1.x or o2.x when Auto is selected.
2. Force STW1.0 = 0 from the PLC. The drive must ramp down on P464 and end in state o1.0. Verify with the trace function (P695) capturing the speed and status word.
3. Force STW1.0 = 1. Drive must accelerate to the last setpoint on the P462 acceleration ramp.
4. Repeat with the other drives commanded ON. The target drive must stop while the others continue without disturbance.
5. Trip the drive by removing the enable (STW1.3 = 0). Issue a fault acknowledge (STW1.7 rising edge). Fault must clear and the drive must return to state o1.0 ready to run.
6. Save parameters (P052 = 1, follow the on-screen menu, do not power down until the PMU shows «save» complete).

11. Fault and Warning Matrix

12. Common Pitfalls and Field-Proven Cautions

• Confusing OFF1 with OFF2. OFF2 (bit 1) is a hard coast and is the safety stop per EN 60204-1. Do not use OFF1 for the e-stop. Wire OFF2 to the safety relay, OFF1 to the PLC.
• Bit polarity. STW1 bit 0 is active high: 1 = run, 0 = ramp stop. PLC code that negates the wrong way will latch the drive in OFF1 indefinitely.
• Free-function-block pre-emption. If P590 is misconfigured, the FFB output can override the fieldbus bit and the PLC cannot stop the drive. Always read back r000 after every parameter change.
• Save before power down. The SIMOVERT MASTERDRIVES parameter save (P052) is not instantaneous. Cutting DC within 5 s of issuing the save corrupts the EEPROM and reverts to defaults on next power-up.
• Encoder feedback on 1FK7. P130 must match the absolute encoder variant; an incorrect value lets the motor run uncontrolled in a no-load state but the OFF1 ramp will still fail because the speed controller will saturate.

13. Quick-Reference Parameter Sheet

FAQ