SEW MOVIDRIVE bus positioning

SEW MOVIDRIVE ®  Bus Positioning: A Complete Guide to Project Planning, Installation, Debugging, and Troubleshooting

Introduction

In modern automation systems, precise positioning is a key technology in areas such as material handling, warehousing logistics, and robotics. SEW-EURODRIVE for MOVIDRIVE ®  The MDV60A/MDS60A frequency converter provides Bus Positioning based on fieldbus or system bus, which is integrated into the MOVITOOLS software package as an IPOSplus program and can achieve multi axis position control without complex programming. This article is based on the official supplementary explanation (document number 0918 421x, 2018-2020 version), which systematically explains the application scenarios, hardware requirements, installation and wiring, startup and debugging, parameter configuration, and typical fault handling of bus positioning, providing engineers with a complete technical operation manual.

Project Planning

1.1 Application Fields

Bus positioning is particularly suitable for the following industries and scenarios:

Material handling: electric hoist, rail vehicle, shuttle car

Logistics warehousing: elevated warehouse stacker crane, horizontal moving trolley

Stacking/handling: Multi axis robotic arm, gantry frame

Its core advantages lie in a user-friendly interface, requiring only basic parameters (speed ratio, diameter, speed) to be entered, no programming experience required, supporting monitoring mode diagnosis, and quick start-up.

1.2 Software and hardware requirements

1.2.1 PC and Software

Operating System: Windows 95/98/NT 4.0

Software: MOVITOOLS (including bus positioning program)

1.2.2 Frequency converter, motor and encoder

Variable frequency drive type:

MOVIDRIVE ®  MDV60A (asynchronous servo/AC motor)

MOVIDRIVE ®  MDS60A (synchronous servo motor)

Fieldbus option card (installed in OPTION1 slot):

PROFIBUS → DFP11A

INTERBUS → DFI11A

CAN bus → DFC11A

DeviceNet → DFD11A

System bus SBus (standard, no option card required)

Motor and Feedback:

MDV60A+CT/CV asynchronous servo motor (with built-in encoder)

MDV60A+DT/DV/D AC motor (requires incremental encoder or combination encoder AV1Y)

MDS60A+DS/DY synchronous servo motor (with built-in rotary transformer)

External encoder (required for non rigid connections):

Incremental encoder → connected to basic unit X14

Absolute value encoder → connected to DIP11A option card X62

If it is a rigid connection (no relative sliding between the motor shaft and the load), an external encoder is not required; But external encoders can also be configured in a non rigid connection manner.

Connection type: rigid connection, non rigid connection

External encoders are not required (incremental or absolute)

Reference operation requires

Absolute encoder interface DIP11A is not required for absolute value encoders only

1.3 Function Description

Bus positioning achieves the following functions through fieldbus or system bus:

Any number of target positions can be defined and selected through PLC

The maximum stroke depends on the set stroke unit (1/10 mm → 3.27 m; mm → 32.7 m; cm → 327 m)

Support software limit switches

Support incremental or absolute value external encoders

Three operating modes: jog mode, reference mode, and automatic mode

Process data exchange (as shown in Figure 1):

Output data (PLC → frequency converter): control word (PO1), set speed (PO2), set position (PO3)

Input data (frequency converter → PLC): status word (PI1), actual speed (PI2), actual position (PI3)

1.4 Driving Scaling

The control system needs to know the number of encoder pulses (in inches/mm) corresponding to each stroke unit. The zoom function allows customization of user units (such as mm, m, cm, 1/10 mm, etc.).

No external encoder (rigid connection)

Automatically calculate scaling factor at startup

Required inputs: drive wheel diameter (or screw pitch), gearbox reduction ratio (i_gear), additional reduction ratio (i_additional)

Calculation formula: Number of pulses=4096 × i gauge × i additional, distance=π × diameter or pitch

Speed scaling: numerator (rpm) and denominator (mm/s, optional m/min or rpm)

There is an external encoder (non rigid connection)

External encoder activation and scaling must be completed in the Shell before starting bus positioning:

P941 "Source actual position" is set to EXT. ENCODER (X14) or APPROLUTE ENCODER (DIP)

Set P942~P944 encoder factors (numerator/denominator) and external encoder scaling

The automatic scaling function is blocked during startup

1.5 Limit switch, reference cam, and machine zero point

The software limit switch must be within the travel range of the hardware limit switch

The reference position and software limit switch must not overlap, otherwise fault F78 will occur

Reference offset: By setting the offset, the machine zero point can be changed without moving the reference cam. Formula: Machine zero point=reference position+reference offset

1.6 Process Data Allocation

Process output data (PO1~PO3):

PO1 control word 2: bit 0=reserved; Position 1=Enable/Quick Parking; Bit 2=Enable/Stop; Bit 3=Fault reset; Bit 4=reserved; Position 5=set position (automatic mode); Bit 6=fault reset (remains at 1 to remove limit); Bit 8=Start (Reference/Auto); Position 9=jog forward rotation; Bit 10=jog reversal; Position 11-12=mode selection (00=invalid, 01=jog, 10=reference, 11=automatic)