In high-end industrial automation applications, frequency converters often need to expand more analog signal processing and high-speed feedback interfaces to meet the needs of complex motion control. The EM-ENC-04 expansion module provided by Bonfiglioli for the ACTION and ACTION Cube series frequency converters is a versatile solution tailored to this demand. It integrates a second high-speed encoder interface with zero pulse detection, bipolar analog input, bipolar analog output, and relay digital output, providing a one-stop hardware expansion platform for complex drive systems.
Chapter 1: EM-ENC-04 Hardware Architecture and Installation
EM-ENC-04 is a high-end model in the Bangfeili ACT/ACU inverter expansion module series, installed in the lower slot of the device. Its hardware architecture includes four major functional modules: high-speed encoder input (including zero pulse detection), bipolar analog input (± 10V/± 20mA, 12 bit resolution), bipolar analog output (± 10V), and relay output (normally open contacts).
1.1 Overview of Hardware Function Modules
According to Chapter 2 of the manual, EM-ENC-04 provides the following functions:
Speed sensor input (second encoder): Incremental encoder interface, supports A/B/Z three channel differential signals, maximum input frequency of 300 kHz, supports quadruple frequency evaluation and zero pulse monitoring.
Analog input EM-S1INA: Bipolar analog input, switchable to ± 10V voltage input or ± 20mA current input through DIP switch S1, with 12 bit resolution.
Analog output EM-S1OUTA: Bipolar ± 10V voltage output, can output different actual values through parameter configuration.
Digital output EM-S1OUTD: Relay output (normally open contact), maximum 24V AC/DC, 1A resistive load.
1.2 Mechanical Installation and Safe Operation
The installation process must strictly follow the following safety steps (Chapter 3.2):
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-04 is pre installed in the housing, and touching the exposed PCB board on the back is prohibited to prevent electrostatic discharge (ESD) from damaging components.
Cover plate reset: After installation, the lower cover plate needs to be reinstalled in place.
1.3 Definition of Wiring Terminals
EM-ENC-04 provides two connection sockets X410A and X410B (Chapter 3.3.2):
X410A (encoder input and power supply):
Terminal 1-2: Encoder A+/A - signal
Terminal 3-4: Encoder B+/B - signal
Terminal 5-6: Encoder Z+/Z - (zero pulse reference signal)
Terminal 7: 5V power output (used to power the encoder, maximum 200mA)
X410B (Analog I/O and Relay Output):
Terminal 1:20V power output (maximum 180mA)
Terminal 2: Ground (GND)
Terminal 3: Analog output EM-S1OUTA (± 10V)
Terminal 4: Analog input EM-S1INA (± 10V or ± 20mA)
Terminal 5-6: Relay output EM-S1OUTD (normally open contact)
Chapter 2: Encoder Interface Configuration with Zero Pulse
The core differentiation function of EM-ENC-04 is its support for A/B/Z three channel incremental encoder interfaces, where the Z channel (zero pulse) can be used for encoder monitoring and position reference.
2.1 Encoder working mode selection
Select the operating mode through the parameter Operation Mode Speed Sensor 2 493 (Chapter 4.4):
0 (Off): Speed measurement disabled
4 (Quadruple Evaluation): Quadruple Evaluation - Counting the four edges of A/B signals to achieve the highest resolution speed measurement.
104: Same as Mode 4, but the speed value is reversed.
1004 (Quadruple Evaluation with Pulse): Quadruple frequency evaluation+zero pulse monitoring - Z signal is used for encoder reliability monitoring.
1104: Same mode as 1004, but the speed value is reversed.
2.2 Hardware signal compatibility and terminal resistance
The interface supports two signal types, which can be selected through the parameter Level 495 (Chapter 4.4.3):
Level=0 (push-pull/differential): A 5V differential signal (A+/A -, B+/B -, Z+/Z -) that complies with the RS-422A/RS-485 standard, with strong anti-interference ability.
Level=2 (single ended): 10V~24V single ended HTL signal, only using A+, B+, Z+terminals.
Terminal resistor configuration (DIP switch S2) (Chapter 4.4.1):
For 5V RS-422 differential signals, the built-in 150 Ω terminal resistor can be activated through S2:
Both switches of S2 are turned on to activate the terminal resistor (only applicable to 5V push-pull signals)
Both switches of S2 are turned off: the terminal resistor is not activated
Key warning: The two switches of S2 must be placed in the same position at the same time, otherwise it may damage the components. For 24V single ended signals, there is no need to activate terminal resistors.
2.3 Encoder line count calculation and parameterization
The number of encoder lines is set through Division Marks Speed Sensor 2 494 (range 1~8192, default 1024).
The maximum allowable number of lines is determined by the upper limit of the input frequency (300 kHz) and the maximum speed (Chapter 4.4.2):
Smax=three hundred thousand Hz×sixty s/min nmax
S max=300000Hz× n max 60s/min
Minimum line requirement: To ensure low-speed stability, the signal should be updated at least every 2ms
Smin=five hundred Hz×sixty s/min four × nmin
S min=500Hz× 4×n min 60s/min
2.4 Actual speed source switching
Select the feedback source for the speed controller through Actual Speed Source 766 (Chapter 4.4.4):
1: Use the encoder input of the basic device (default)
2: Use the second encoder input of EM-ENC-04
2.5 Zero pulse monitoring function
When selecting mode 1004 or 1104, the frequency converter will continuously monitor the integrity of the Z signal. If the Z signal is abnormal or does not match the A/B signal, it will trigger an encoder fault (Chapter 6.1):
F1433: Encoder 2 Division marks wrong
F1434: Encoder 2 division mark too low
F1435: Encoder 2 division mark too high

Chapter 3: Bipolar Analog Input Configuration
The analog input of EM-ENC-04 provides a bipolar range of ± 10V/± 20mA, a 12 bit resolution, and can be flexibly configured through hardware and software.
3.1 Voltage/Current Mode Switching (DIP Switch S1)
S1=OFF (right side): Voltage input mode (± 10V, input impedance 100k Ω)
S1=ON (left side): Current input mode (± 20mA, input impedance 250 Ω)
3.2 Programmable signal characteristic curve
The process of simulating input mapping to reference values is defined by two linear characteristic curves (Chapter 4.1.3):
Characteristic Point X1/Y1 564/565: Coordinates of the first point (input signal% → output reference%)
Characteristic Point X2/Y2 566/567: Second Point Coordinates
3.3 Operation Mode 562 (Chapter 4.1.4)
1- Bipolar: Mapping complete ± 100% input to ± 100% output.
11- Monopolar: The negative input signal is mapped to 0.
21- Monopolar 2-10V/4-20mA: Suitable for standard industrial signals, the lower limit of the input range is fixed at 20% (2V/4mA).
101- Bipolar Absolute Value: Bipolar input is mapped to unipolar output (in absolute value).
3.4 Tolerance Bands and Error Behavior (Sections 4.1.6, 4.1.7)
Tolerance Band 560: Set zero dead zone to prevent frequent direction switching caused by noise.
Error/Warning Behavior 563:
1 (Warning): A warning is issued when the signal is below 1V/2mA.
2 (Stop): When the signal is lost, perform the stop action 2 to slow down and stop the machine.
3 (Fault tripping): Immediately stop freely and report an error when the signal is lost.
3.5 Analog Input Calibration (Chapter 4.1.8)
Perform two-stage calibration through Adjustment 568:
Apply 0V (or 0mA) input and execute Adjustment=1.
Apply 10V (or 20mA) input and execute Adjustment=2.
Chapter 4: Bipolar Analog Output Configuration
EM-ENC-04 provides ± 10V bipolar analog output, which can flexibly map different actual values (Chapter 4.2).
4.1 Operation Mode 584
0-Off: Output off (0V, used for calibration)
41- EM-S1INA, absolute value: Output the absolute value of the analog input (0~10V)
100-10V: Fixed output of 10V (for calibration)
101-133: Signed output mode (-10V~+10V)
201-254: Absolute actual value output with a range of 2V~10V (including wire breakage monitoring)
4.2 Zero bias and amplification factor (Chapter 4.2.4)
Offset 585: Zero offset (percentage of ± 10V full-scale, ± 100%)
Amplification 586: Magnification factor (5%~1000%)
Calibration Example:
Select mode 0-Off, measure the output voltage, and fill in Adjustment 587.
Select mode 100-10V, measure the output voltage, and fill in Adjustment 587 again.
Repeat validation, and if the deviation is significant, recalibrate (with an optimal accuracy of approximately ± 40mV).
Chapter 5: Relay Digital Output Configuration
EM-ENC-04 provides independent relay outputs (normally open contacts) that can be used to drive external contactors, indicator lights, or as fault signal outputs (Chapter 4.3).
5.1 Operation Mode EM-S1OUTD 533
The optional operating modes are consistent with the digital output in the basic equipment of the frequency converter (see the "Digital Output" chapter of the frequency converter operation manual), including:
Running signal
fault signal
Frequency arrival
Current limit activation
Brake control, etc
Chapter 6: Reference Channel Expansion
Both the analog input and encoder input of EM-ENC-04 can be used as reference value sources for the frequency converter (Chapter 4.5), and can be selected through Reference Frequency Source 475 or Reference Percentage Source 476:
2: Only EM-S1INA analog input is used as a reference source
4: MFI1A+EM-S1INA overlay
12: EM-S1INA+fixed frequency superposition
34: Second encoder (speed sensor 2) as reference source
35: MFI1A+Second Encoder Overlay
102-135: Corresponding patterns with symbols
Chapter 7: Fault Diagnosis and Troubleshooting
EM-ENC-04 extends the fault diagnosis capability of the frequency converter and adds fault codes related to the encoder Z signal (Chapter 6.1):
Analog input fault:
F1402: Analog input EM-S1INA signal fault (signal loss or overload), check X410B. 4 wiring and signal source.
Encoder malfunction:
F1430: There is no signal from the encoder signal. Check the A+/A - and B+/B - wiring of X410A.
F1431: A or B phase signal missing (single channel loss), check if the cable is open circuit.
F1432: Rotation direction error (A/B phase sequence reversed), can be corrected by swapping A+and B+wiring.
F1433: Encoder 2 division mark error (Z signal abnormal), check if the Z+/Z - wiring and encoder zero pulse signal are normal.
F1434: The division mark of encoder 2 is too low (the number of detected lines is lower than the set value). Check if the set value of parameter 494 is too high.
F1435: The division mark of encoder 2 is too high (the number of detected lines is higher than the set value). Check if the set value of parameter 494 is too low.
