In the engineering practice of frequency converter drive systems, motor overheating protection is a key link to ensure equipment safety and continuous operation. Traditional thermal relays or bimetallic switches only provide simple switch protection, while temperature monitoring based on PTC thermistors can achieve more accurate and configurable temperature warning and fault response. The Bonfiglioli Vectron ACTION and ACTION Cube series frequency converters integrate a dedicated PTC thermistor input port through the EM-IO-02 expansion module, providing standard I/O expansion and CAN system bus communication, making motor temperature monitoring a standardized and parameterized system function.
This article is based on the EM-IO-02 extension module technical manual, providing a systematic technical operation guide for the core concerns of on-site engineers in installation, wiring, system bus configuration, and parameterization of motor temperature monitoring.
Overview and Functional Positioning of EM-IO-02 Expansion Module
1.1 Module Core Functions
EM-IO-02 is an optional hardware expansion component designed by Bonfiglioli Vectron for the ACTION and ACTION Cube series frequency converters, supporting software versions 4.1.0 and higher for the ACTION series and all ACU series devices. This module achieves the following functional extensions by inserting it into the lower expansion slot of the frequency converter:
CAN system bus interface: compliant with ISO-DIS 11898 (CAN High Speed) standard, supporting a maximum communication rate of 1 MBaud
Second bipolar analog input: 12 bit resolution, configurable for ± 10V voltage or ± 20mA current input
Second bipolar analog output: ± 10V voltage output, overload and short circuit protection
Three channel digital input: PLC compatible, 24V level, supports up to 150kHz frequency signal, can be used as speed sensor input
One way relay output: normally open contact, 24V AC/DC, 1A (resistive load)
PTC thermistor input: compliant with DIN 44081 standard, rated response resistance value of 2.85k Ω
1.2 Functional differences between EM-IO-01 and EM-IO-02
Compared with EM-IO-01, the core differentiating function of EM-IO-02 lies in motor PTC temperature monitoring:
Functional Comparison EM-IO-01 EM-IO-02
CAN system bus support
Analog input 1 channel (12 bits) 1 channel (12 bits)
Analog output 1 channel (± 10V) 1 channel (± 10V)
Digital input with 3 channels and 3 channels
Relay output 2 channels and 1 channel
PTC temperature input not supported (X410B. 1-2)
Key points of mechanical and electrical installation
2.1 Mechanical Installation
The mechanical installation steps of EM-IO-02 are exactly the same as those of EM-IO-01:
Power off confirmation: The frequency converter must be completely powered off and wait for the DC bus capacitor to discharge completely (several minutes).
Disassemble the lower cover plate: Remove the plastic cover plate on the lower part of the frequency converter.
Insertion module: Align the EM-IO-02 expansion module with the slot and apply even force to insert it, taking care to only hold the housing and avoid contact with the PCB.
Reset cover plate: Reinstall the lower cover plate.
2.2 Electrical Connections - Detailed Explanation of Terminal Definitions
EM-IO-02 provides two sockets: X410A and X410B.
Socket X410A (terminals 1-7):
Technical parameter description of terminal signal
1 20V output Imax=180mA to power external sensors
2 20V ground - corresponding to terminal 1 ground
3-digit input 1 (EM-S1IND) Umax=30V, 10mA@24V Response time is about 16ms
4-digit input 2 (EM-S2IND) can be used as the speed sensor Track A as above
5 digital inputs 3 (EM-S3IND) can be used as the speed sensor Track B as above
6-7 relay output (EM-S1OUTD) 24V AC/DC, 1A normally open contact
Socket X410B (terminals 1-7) - The PTC interface is located in this socket:
Technical parameter description of terminal signal
1-2 PTC Input (EM-MPTC) Rated Response Resistance 2.85k Ω (DIN 44081) Motor Temperature Monitoring
3 analog inputs (EM-S1INA) ± 10V/± 20mA, 12 bit second channel analog input
4 Analog Output (EM-S1OUTA) ± 10V, Imax=2mA Second Analog Output
5 CAN_Low - System Bus CAN Low Line
6 CAN-High - System Bus CAN High Line
7 CAN_SND - System Bus Ground
Key tip: Terminal X410B. 1-2 is a dedicated PTC thermistor input port that can be connected to PTC sensors or bimetallic temperature sensors (normally closed contacts) that comply with DIN 44081 standards.
2.3 Analog input voltage/current mode switching
The dip switch S3 on the module is used to configure the analog input signal type:
S3=OFF (right side): Voltage signal (± 10V)
S3=ON (left side): Current signal (± 20mA)
S1 and S2 switches are used for configuring the terminal resistance of the system bus (see System Bus chapter for details).
PTC Motor Temperature Monitoring - Detailed Explanation of Core Functions
3.1 Working principle of PTC monitoring
The resistance of PTC (Positive Temperature Coefficient) thermistor increases sharply with increasing temperature. When the temperature of the motor winding exceeds the rated threshold (usually 130 ° C~180 ° C, depending on the insulation level of the motor), the PTC resistor jumps from several hundred ohms to several thousand ohms. The frequency converter detects this change in resistance and triggers a warning or fault shutdown.