Bonfiglioli Vectron EM-IO-01 Expansion Module Installation and System Bus Configuration Guide

CAN system bus configuration

4.1 Bus topology and terminal resistance

The system bus of EM-IO-01 adopts CAN High Speed physical layer, which complies with ISO-DIS 11898 standard. The bus topology is a linear structure (daisy chain), and terminal resistors must be set at the first and last physical nodes.

The module is configured with terminal resistors through dip switches S1 and S2

Passive terminal (S1=ON, S2=OFF): Conventional terminal matching

Active terminal (S1=ON, S2=ON): Active terminal, can improve the shape of CAN signal edges, suitable for long-distance buses

Factory default: S1 and S2 are both OFF (terminal resistance not activated).

Important note: Active terminals can only be activated on one node of the bus, and other nodes must use passive terminals. Improper configuration of terminal resistors will result in bus communication errors.

4.2 Node ID Setting

The system bus supports up to 63 slave nodes (frequency converters), and each node must have a unique Node ID. Node ID is set through parameter 900:

Parameter Description Minimum Value Maximum Value Factory Value

900 Node-ID -1 63 -1

Node ID=-1: The system bus disables this frequency converter

Node ID=0: Define this frequency converter as the bus master station (only one master station is allowed)

Node ID=1~63: Slave address

4.3 Baud rate and bus length

All bus nodes must be set to the same baud rate. The baud rate is set through parameter 903 and determines the maximum bus length:

Maximum line length for operating mode baud rate

3 50 kBaud 1000 meters

4 100 kBaud 800 meters

5 125 kBaud 500 meters

6 250 kBaud 250 meters

7500 kBaud 100 meters

8 1000 kBaud 25 meters

Engineering Tip: Baud rates below 50 kBaud are not recommended for low data throughput on the system bus. The actual maximum line length needs to be calculated and verified based on cable parameters and bus driver (PCA82C250T).

System bus communication mechanism

The system bus of the EM-IO-01 module is based on the CANopen protocol framework (CiA DS 301), which enables communication between Network Management (NMT), Process Data Objects (PDO), and Service Data Objects (SDO).

5.1 Network Management (NMT) and Startup Sequence

The node state machine on the system bus contains three main states:

Pre Operational: Only SDO communication (parameter read/write) is allowed, PDO (process data) is prohibited

Operational: Both SDO and PDO are allowed

Stopped: Both SDO and PDO are prohibited

Typical startup sequence:

After power on, all slave stations complete initialization and enter Pre Operational state

Send Boot Up message from the slave station (identifier=1792+Node-ID, data byte=0x00)

The master station switches the slave station to Operational state through the NMT command "Start Remote Node" (command code=1)

After initialization is completed, the master station periodically sends the Start Remote Node command with the delay time set by parameter 904 (Boot Up Delay) to ensure that the slave stations that are delayed online or temporarily disconnected can resume normal communication

Main station fault response: When the main station receives an Emergency Message from the slave station, its response is set by parameter 989 (Emergency Reaction):

989=0 (Error): The master station shuts down simultaneously and reports the fault to the slave station through fault code F21nn (nn is the hexadecimal of the slave station Node ID)

989=1 (No Error): The main station only reports a warning (Sysbus 0x2000)

5.2 SDO Channel (Parameter Data)

Each frequency converter has two SDO channels for parameter data exchange:

SDO1: Used for parameterized access of slave stations by the master station (PLC/PC or frequency converter master station)

SDO2: Reserved for parameterization by visualization tools (such as VPlus software)

The SDO channel adopts the CANopen SDO Segment Protocol Expedited service, which supports read and write of uint/int/long type data. Complete parameterization can be achieved through the system bus.

SDO1 identifier allocation (Predefined Connection Set):

Rx-SDO1=1536+Node ID (identifier range 1537~1599)

Tx-SDO1=1408+Node ID (identifier range 1409~1471)

Fixed allocation of SDO2 identifiers:

Rx-SDO2 = 1600 + Node-ID

Tx-SDO2 = 1472 + Node-ID

Note: In CANopen systems, SDO2 must be disabled to avoid compatibility issues. The activation state of SDO2 can be controlled through parameter 923 (SDO2 Set Active).

5.3 PDO channel (process data)

Each frequency converter has three PDO channels (three Rx/Tx each) for high-speed process data exchange. The PDO channel can operate in two modes: time control or SYNC control.

PDO identifier allocation (Predefined Connection Set):

Channel Rx identifier Tx identifier

PDO1 512 + Node-ID 384 + Node-ID

PDO2 768 + Node-ID 640 + Node-ID

PDO3 1024 + Node-ID 896 + Node-ID

Operation mode setting:

TxPDO Function (parameters 930/932/934): 0=disabled, 1=time control, 2=SYNC control

RxPDO Function (parameters 936/937/938): 0=time control (immediate forwarding), 1=SYNC control

Attention: The identifier range of 129~191 is reserved for emergency messages and cannot be used for PDO allocation.

5.4 Virtual Links

The most distinctive feature of the system bus is the virtual link mechanism. By linking the source data to the sending byte of TxPDO and linking the receiving byte of RxPDO to the target parameter, horizontal data transmission between frequency converters can be achieved.