SEW EURODRIVE MOVIDYN communication interface

SEW MOVIDYN ®  Complete Guide to Communication Interface and Protocol of Servo Controller

Introduction

In modern industrial automation systems, data exchange between the drive controller and the upper control system is the core to achieve precise motion control. SEW-EURODRIVE's MOVIDYN ®  The servo controller series provides a variety of serial communication interfaces (RS-232, RS-485) and rich option cards (PROFIBUS, INTERBUS, CAN, DeviceNet, etc.), supporting flexible multi axis system integration. This article is based on the official communication interface manual (document number 0922 8764) and systematically explains MOVIDYN ®  The serial interface communication protocol, frame structure, application examples, ASCII protocol for API/APA positioning module, RS-232/RS-485 technical parameters, direction control timing, timeout monitoring, and PLC communication examples of servo controllers provide a complete technical operation guide for automation engineers.

Overview of Communication Interface

MOVIDYN ®  The servo controller series (including power module MPB/MPR, compact servo controller MKS, and axis module MAS) are equipped with basic serial interfaces. RS-232 is mainly used for PC connection, while RS-485 supports long-distance multi-point communication. In addition, multiple fieldbuses can be expanded through the option card.

Basic interface configuration:

Each power module and compact servo controller come standard with RS-485 interface

MPB series (with brake chopper) comes standard with RS-232 interface

MPR and MKS can obtain RS-232 interface through USS11 option card

The AIO11 option provides additional analog/digital I/O and RS-232 interfaces

The APx12 option provides single axis positioning control (API12 is an incremental encoder, APA12 is an SSI absolute encoder)

AFI11/AFP11/AFCI1 provide INTERBUS, PROFIBUS, and CAN bus interfaces respectively

Important limitation: RS-485 and RS-232 (or USS11) on the basic unit cannot be used simultaneously because they share the same transmission line.

The communication adopts the master-slave principle: the upper controller (PC, PLC, IPC) serves as the master station, MOVIDYN ®  As a slave station. The slave station never initiates sending and only responds to requests from the master station. The main station always controls the communication link.

Basic Framework of Communication Protocol

To achieve short message, fast response, easy portability, and scalable data transmission, MOVIDYN ®  The serial interface adopts a custom protocol and defines 7 frame types:

Function description of frame type identifier (hex)

ENQUIRY 85 requests to read parameter values

SELECT A9 writes parameter values (standard 4 bytes)

LONG_SELECT AD writes an 8-byte long parameter

DATA C8 responds to ENQUIRY and returns standard parameter values

LONG-DATA CA responds to ENQUIRY and returns an 8-byte parameter value

ACK D2 confirms successful reception of SELECT/LONG_SELECT

NACK F3 denies receipt and carries error code

General composition of frame structure:

Frame identifier (1 byte): Distinguish MOVIDYN ®  Or API/APA data

Unit address (1 byte): Axis module address (0~59, set through the S1 button on the front panel). Can connect up to 31 MKS or 8 MPx+23 MAS

Index (2 bytes): 16 bit parameter index, refer to MOVIDYN ®  Parameter List

Value (4 or 8 bytes): Parameter numerical value (see parameter list for format)

Return code (RC, 1 byte): Only appears in NACK frames, indicating the reason for the error

Checksum (CS, 1 byte): The low byte of the sum of all sent bytes

2.1 Detailed explanation of frame format

ENQUIRY frame

The main station sends a request to read parameters. Format: identifier (85)+address+index (high byte+low byte)+checksum. Reply with DATA or LONG-DATA frame after receiving correctly from the slave station; If there is an error, reply with NACK.

DATA frame

Sent when the slave responds to ENQUIRY. Format: identifier (C8)+index+value (4 bytes)+checksum.

LONG-DATA frame

Used to return 8-byte parameters (such as IPOS variables). Format: Identifier (CA)+Index+Value (8 bytes)+Checksum.

SELECT frame

The main station writes standard parameters (4 bytes). Format: identifier (A9)+address+index+value (4 bytes)+checksum. After success, reply with ACK from the slave station, otherwise reply with NACK.

LONG_SELECT frame

The main station writes 8-byte long parameters (such as IPOS variables). Format: Identifier (AD)+Address+Index+Value (8 bytes)+Checksum.

ACK frame

The slave station confirms successful receipt of SELECT/LONG_SELECT. Format: Identifier (D2)+checksum (checksum equals D2).

NACK frame

Report an error from the station. Format: identifier (F3)+return code (RC)+checksum.

NACK return code list (partial):

Meaning of Return Code (hex)

10 illegal indexes

11 functions/parameters not implemented

12 Read only access

13 parameter lock activated

Factory 14 is currently in operation

15 parameter values are too large

16 parameter value is too small

17 required option cards not installed

1C output stage not prohibited

1D invalid parameter value

Application examples

3.1 Read the temperature of the axis module radiator (Address 12)