Bonfiglioli Vectron EM-SYS System Bus Expansion Module Networking and Virtual Link Configuration Guide

In modern industrial automation, multi axis synchronization and distributed control are key to improving equipment performance. Bonfiglioli provides the EM-SYS system bus extension module for the ACTION and ACTION Cube series frequency converters, which is based on CAN (Controller Area Network) technology to achieve real-time data exchange between frequency converters and between frequency converters and the upper control system.

This article will delve into the hardware installation of the EM-SYS module, CANopen protocol stack application, network management (NMT), SDO/PDO channel configuration, and the core "virtual link" mapping mechanism, providing engineers with a complete reference for networking and debugging techniques.

Chapter 1: EM-SYS Hardware Installation and CAN Bus Physical Layer

The EM-SYS module serves as a system bus expansion component for the frequency converter and is installed in the lower slot of the device.

1.1 Key points for safe assembly

According to the guidelines in Chapter 3 of the manual, the assembly process must strictly follow the following safety steps:

Power off operation: The module installation can only be carried out after the inverter completely cuts off the power and waits for the DC bus capacitor to discharge completely. This is the primary prerequisite for preventing electric shock and equipment damage.

Module insertion: The EM-SYS module is pre installed in the housing, and touching the exposed PCB board on the back is prohibited to prevent electrostatic discharge (ESD) from damaging the components. Align the module with the lower slot and insert it smoothly until it is fully seated.

Cover plate reset: After installation, the lower cover plate needs to be reinstalled in place. After the frequency converter is powered on again, the EM-SYS module automatically enters the ready state.

1.2 CAN Bus Terminal Resistance Configuration

The CAN bus requires terminal resistors to be configured at the first and last nodes of the physical bus to eliminate signal reflections. The EM-SYS module provides flexible terminal configuration options:

DIP switches S1 and S2 (Chapter 4.1):

Passive terminal: Set S1 to ON and S2 to OFF. This is a standard 120 ohm terminal configuration.

Active terminal: Set both S1 and S2 to ON. Active terminals improve signal edge characteristics through bias circuits, making them particularly suitable for long-distance or high interference environments.

Key principle: Active terminals are only allowed to be activated at one point on the bus, and passive terminals must be used for all other terminal nodes. Both S1 and S2 are set to OFF by default at the factory.

1.3 Cable specifications and wiring definitions

Cable type: Twisted pair cables with braided shielding layers must be used, and the use of aluminum foil shielding layer cables is strictly prohibited.

Terminal X410B (Chapter 4.3):

Terminal 4: CAN_GND (signal ground)

Terminal 5: CAN_Low (CAN low line)

Terminal 6: CAN-High (CAN high wire)

Terminal 7: PE (shielded grounding)

Shielding treatment: The shielding layer needs to be connected to the PE (protective ground) with a large area and low impedance at both ends, which is the key to meeting EMC compliance.

Chapter 2: System Bus Protocol Stack and Network Management (NMT)

The system bus protocol of EM-SYS is based on the CANopen (CiA DS 301) standard and adopts a message oriented communication mechanism. Understanding its network management model is the foundation of networking.

2.1 Node Address and Baud Rate Setting

Node ID (Node-ID 900) (Chapter 4.5): Values range from 1 to 63, and each node's address on the bus must be unique.

Node ID=-1 (factory default): The system bus function is turned off.

Node ID=0: Define the frequency converter as the system bus master station. Only one main station is allowed in the entire network.

Baud Rate 903 (Chapter 4.4): The baud rate of all nodes must be consistent, which determines the maximum bus length:

50 kbps → 1000 meters

250 kbps → 250 meters

1000 kbps → 25 meters

2.2 NMT State Machine and Startup Sequence

CANopen defines three NMT states (Sections 4.7, 4.8.1):

Pre Operational: The default state after power on initialization. At this time, only SDO (Parameter Data) communication is allowed, PDO (Process Data) is prohibited.

Operational: PDO communication is activated to achieve real-time data exchange. Meanwhile, SDO can still be accessed.

Stopped: All communication is prohibited.

Main station startup process:

After the main station is powered on and initialized, it needs to wait for a configurable delay time (Boot Up Delay 904, default 3500ms) to ensure that all slave stations complete initialization. Subsequently, the master station sends the NMT command Start Remote Node (command word 0x01, node ID 0x00 represents broadcast) to switch all slave stations from Pre Operational to Operational state, and PDO data exchange begins immediately.

2.3 Emergency message and main station fault response

When a fault occurs at the slave station, an Emergency Message will be sent (Chapter 4.8.3, 4.9.3). The behavior of the main station is determined by the parameter Emergency Reaction 989: