Bonfiglioli Vectron EM-ENC-03 Second Encoder Interface and System Bus Expansion Guide

Bonfiglioli Vectron EM-ENC-03 Second Encoder Interface and CAN System Bus Expansion Guide

In high-performance servo drive and multi axis synchronous control systems, redundant or dual channel speed feedback is often the key to achieving high-precision and high reliability control. The EM-ENC-03 expansion module provided by Bonfiglioli for the ACTION and ACTION Cube series inverters is a streamlined solution designed for this requirement. It integrates the second high-speed incremental encoder interface and CAN system bus function, enabling the frequency converter to connect to the distributed control network and simultaneously receive speed feedback signals from external encoders.

Chapter 1: EM-ENC-03 Hardware Architecture and Installation Points

EM-ENC-03, as a functional expansion component of the frequency converter, is installed in the lower slot of the device. Unlike the more feature rich EM-ENC-02, EM-ENC-03 focuses on two core functions: high-speed encoder input (second encoder) and CAN system bus (CANopen protocol stack).

1.1 Hardware functional modules

According to the instructions in Chapter 2 and Chapter 3 of the manual, EM-ENC-03 provides the following functions:

CAN system bus interface: compliant with ISO-DIS 11898 (CAN High Speed) standard, supporting a maximum transmission rate of 1 MBaud, used for real-time data exchange between frequency converters.

Speed sensor input (second encoder): differential/push-pull encoder interface, maximum input frequency of 300 kHz, supports quadruple frequency evaluation of A/B dual channel signals.

1.2 Mechanical Installation and Safe Operation

The installation process must strictly follow the following safety steps:

Safe power-off: The module installation can only be carried out after the frequency converter has completely cut off the power and waited for the DC bus capacitor to discharge (at least 3 minutes).

Module insertion: EM-ENC-03 is pre installed in the housing, and touching the exposed PCB board on the back is prohibited to prevent damage to components caused by electrostatic discharge (ESD). 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 powering on again, the module automatically enters the ready state.

1.3 Definition of Wiring Terminals

EM-ENC-03 provides two connection sockets (Chapter 3.3.2):

X410A (encoder input):

Terminal 1: Encoder A+signal

Terminal 2: Encoder A - Signal

Terminal 3: Encoder B+signal

Terminal 4: Encoder B - Signal

Terminals 5 and 7: Undefined (no function)

Terminal 6: Ground (GND)

X410B (CAN system bus):

Terminal 5: CAN_L (CAN low line)

Terminal 6: CAN-H (CAN high wire)

Terminal 7: CAN_GND (CAN signal ground)

Terminals 1-4: Undefined (no function)

Chapter 2: 300kHz High Speed Encoder Interface Configuration

The core function of EM-ENC-03 is its second high-speed encoder interface, which supports input frequencies up to 300 kHz and is suitable for closed-loop control applications with high-resolution encoders and high dynamic response.

2.1 Hardware signal compatibility and terminal resistance configuration

The encoder interface selects the working mode through the parameter Operation Mode Speed Sensor 2 493 (Chapter 5.1):

0 (Off): Speed measurement disabled

4 (Quadruple Evaluation): Quadruple Evaluation - Counting the four edges of the A/B signal can achieve the highest resolution speed measurement, recommended for high-precision speed closed-loop.

104 (Quadruple Evaluation Inverted): Same as Mode 4, but with the velocity value reversed (equivalent to exchanging A/B phase signals).

The interface is compatible with two signal types, which can be selected through the parameter Level 495 (Chapter 5.1.3):

Level=0 (push-pull/differential): A 5V differential signal (A+/A -, B+/B -) that complies with the RS-422A/RS-485 standard, with strong anti-interference ability and suitable for long-distance transmission.

Level=2 (single ended): 10V~24V single ended HTL signal, only using A+and B+terminals, suitable for traditional industrial encoders.

Terminal resistor configuration (DIP switch S3) (Chapter 5.1.1):

For 5V RS-422 differential signals, the built-in 150 Ω terminal resistor can be activated through DIP switch S3:

Both switches of S3 are placed in the ON position: activate the terminal resistor

Both switches of S3 are in the OFF position: the terminal resistor is not activated

Key warning: The two switches of S3 must be placed in the same position at the same time, otherwise it may cause damage to the components. For 24V single ended HTL signals, there is no need to activate terminal resistors.

2.2 Encoder line count calculation and parameterization

The number of lines (PPR pulses per revolution) of the encoder is set through the parameter Division Marks Speed Sensor 2 494 (range 1~8192, default 1024).

Maximum allowable line count calculation (Chapter 5.1.2):

The maximum number of lines is determined by the upper limit of the encoder input frequency (300 kHz) and the maximum motor speed:

Smax=three hundred thousand Hz×sixty s/min nmax

S max=300000Hz× n max 60s/min 

among which nmax

The maximum speed (RPM) of the motor.

Minimum number of lines required:

To ensure smooth operation at low speeds, the encoder signal should be updated at least every 2ms (signal frequency ≥ 500Hz). The formula for calculating the minimum number of lines is:

Smin=five hundred Hz×sixty s/min four×nmin

S min=500Hz× 4×n min 60s/min

The coefficient 4 represents the fourth harmonic evaluation,nmin

The minimum operating speed (RPM) of the motor.

2.3 Actual speed source switching

After the second encoder of EM-ENC-03 is connected, the feedback source of the speed controller can be selected through the parameter Actual Speed Source 766 (Chapter 5.1.4):

1 (Speed Sensor 1): Use the encoder input of the basic device (default)

2 (Speed Sensor 2): Use the second encoder input of EM-ENC-03

This feature allows users to flexibly switch between two encoders or switch to a backup encoder in case of a main encoder failure, achieving redundant feedback.

2.4 Encoder signal fault diagnosis

EM-ENC-03 extends encoder fault detection capability (Chapter 7.1):

F1430: Encoder signal fault (no signal), check the A+/A -, B+/B - wiring and encoder power supply of X410A.

F1431: Encoder single channel signal missing (phase A or B lost), check if the cable is open or has poor contact.

F1432: Encoder rotation direction error (A/B phase signal reversed), can be corrected by swapping A+and B+wiring.

Chapter 3: CAN System Bus and CANopen Protocol Stack

EM-ENC-03 integrates the complete CAN system bus function (Chapter 4), based on the CANopen protocol (CiA DS301), to achieve real-time data exchange and distributed control between frequency converters.

3.1 Node Address and Baud Rate Configuration

Node-ID 900 (Chapter 4.5): Set the node address (range -1~63). -1 is disabled (factory default), 0 is master mode. Only one main station is allowed in the network.

Baud Rate 903 (Chapter 4.4): Supports baud rate settings from 50 kbps to 1000 kbps. The lower the baud rate, the longer the allowed bus length (such as 50 kbps → 1000 meters, 1000 kbps → 25 meters).

3.2 Bus Terminal Resistance Configuration (DIP Switches S1 and S2)

The CAN bus requires terminal resistors to be configured at the first and last nodes of the physical bus (Chapter 4.1):

Passive terminal: S1=ON, S2=OFF (standard 120 Ω terminal)

Active terminal: S1=ON, S2=ON (improves signal edge through bias circuit, suitable for long-distance bus)

Key rules:

Active terminals are only allowed to be activated at one location within the network

Other terminal nodes must use passive terminals

Factory default S1 and S2 are both OFF

3.3 NMT State Machine and Network Startup Sequence

The system bus of EM-ENC-03 follows the CANopen NMT (Network Management) state machine (Sections 4.7, 4.8.1):

Three NMT states:

Pre Operational: The default state after power on initialization. Only SDO (Parameter Channel) is available, PDO (Process Data) is disabled.

Operational: Activate PDO communication 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, wait for a configurable delay time (Boot Up Delay 904, default 3500ms), and then send the NMT command Start Remote Node (command word 0x01, node ID 0x00 represents broadcast) to switch all slave stations to Operational state.

3.4 Emergency message and main station fault response

When a fault occurs at the slave station, an Emergency Message is sent with an identifier of 128+Node ID (Chapter 4.8.3). The behavior of the main station is defined by the parameter Emergency Reaction 989:

989=0 (Error): After receiving an emergency message, the master station also tripped and reported fault F21nn (nn is the hexadecimal node ID of the faulty slave station), while the warning bit Sysbus (0x2000) was set.

989=1 (No Error): The main station only displays a warning and does not trigger its own trip.

Chapter 4: PDO Channel and Virtual Link Data Mapping

EM-ENC-03 supports three sets of PDO (Process Data Object) channels for real-time process data exchange between frequency converters (Chapter 4.11).

4.1 PDO identifier allocation

The default identifier follows the CANopen predefined connection set:

TxPDO1：384 + Node-ID

RxPDO1：512 + Node-ID

TxPDO2：640 + Node-ID

RxPDO2：768 + Node-ID

TxPDO3：896 + Node-ID

RxPDO3：1024 + Node-ID

Identifier uniqueness rule:

All TxPDO identifiers must be unique in the bus network

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

4.2 PDO working mode

Each PDO channel can be configured as (Chapter 4.11.2):

Time control: TxPDO sends cyclically at fixed time intervals (such as TxPDO1 Time 931); RxPDO forwards the data immediately after receiving it.

SYNC control: TxPDO sends the SYNC synchronization message uniformly after receiving it; RxPDO forwards data only after receiving SYNC. This mode is suitable for multi axis synchronous locking scenarios.

4.3 PDO timeout monitoring

Can enable RxPDO timeout monitoring (Chapter 4.11.3):

SYNC Timeout 939: Monitoring SYNC message timeout

RxPDO1/2/3 Timeout 941/942/945: Monitoring each RxPDO data update timeout

Timeout will trigger faults: F2200 (SYNC timeout), F2201-F2203 (RxPDO timeout)

4.4 Virtual Link Mapping Mechanism

EM-ENC-03 uses the "Sources and Links" method to implement data mapping (Chapter 4.11.5), without the need for complex CANopen mapping parameters.

TxPDO packaging (sender):

The 8 bytes of each TxPDO can specify the data source through parameters:

Boolean variable: Source number 6/7 (True/False) or 70-72 (numeric input)

Word variables: source numbers 9063/9064 (reference percentage), etc

Long variables: source number 900 (output frequency) or 1-5 (fixed frequency), etc

RxPDO unpacking (recipient):

The receiver's RxPDO maps the data to available source numbers (700-729) and connects them to the local functional input through parameters. For example, source number 704 can be used as a control word input source.

Chapter 5: Channel Expansion of Frequency Reference Values

The second encoder of EM-ENC-03 can be used as a reference value source for the frequency converter (Chapter 5.2), and can be selected through Reference Frequency Source 475:

34 (Speed Sensor 2, absolute value): Use the frequency signal of the second encoder directly as a reference value.

35 (MFI1A+Speed Sensor 2): Overlay the multifunctional analog input with the second encoder signal.

134/135: Corresponding patterns with symbols.

This feature allows users to implement advanced applications such as "electronic gears" or "master-slave following".

Chapter 6: System Bus Capacity Planning

Before building a multi node system bus network, capacity calculation must be performed (Chapter 4.14.3). Each PDO frame is about 140 bits, and the bus load rate needs to be controlled within a safe range:

≤ 80%: Normal (OKAY)

80-90%: Critical

>90%: Not feasible, may result in message loss