Eight MOSFETS with PWM card for Raspberry Pi Back Panel with 4 high voltage 4A/250VDC and 4 high current 8A/48VDC outputs, isolated inputs, and connectors.

8-MOSFETS with PWM for Raspberry Pi Back Panel bottom view

8-MOSFETS with PWM for Raspberry Pi Back Panel with OLED display

8-MOSFETS with PWM on Raspberry Pi Back Panel

8-MOSFETS with PWM on Raspberry Pi Back Panel enclosed

SKU: SM-P-770

Eight MOSFETS with PWM, Current Sense and Digital Inputs for Raspberry Pi Back Panel

Name: Eight MOSFETS with PWM, Current Sense and Digital Inputs for Raspberry Pi Back Panel
Brand: Sequent Microsystems
SKU: SM-P-770
Price: 100.0 USD
Availability: OutOfStock

Eight MOSFETS with PWM, up to 8A and 240VDC loads, proportional control with current sensing

Coming soon

$100.00

Product variants

The Eight MOSFETS with PWM card features four high current outputs driving 8A and 48VDC loads and four high voltage outputs driving 4A and 240VDC loads. Each output is PWM controlled and has current measuring and current limiting capability. Each group of four MOSFETS is galvanically isolated. In adition, eight isolated inputs can read active high signals from 3V to 24VAC or DC.

Seamlessly integrated with the Raspberry Pi Back Panel, the card supports MODBUS RTU over RS485, OpenPLC, and CODESYS.

FEATURES

Key Features

Plugs directly into the Raspberry Pi Back Panel — no additional wiring or hardware needed
Four galvanically isolated 8A/48VDC with 1Khz PWM MOSFET outputs
Four galvanically isolated 4A/240VDC with 1KHz PWM MOSFET outputs
Current sensing on all outputs
Eight optically isolated 24V PNP inputs
TVS protection on all outputs
LED indicators on all inputs and outputs
ECCN classification: EAR99
Open source hardware - schematics available

DESCRIPTION

Part of the HOP (Hardware On Panel) family developed by Sequent Microsystems, the Eight MOSFETS with PWM card plugs directly in the Sequent Microsystems Back Panel.

Up to eight HOP cards—of any type—can be installed on a single Back Panel, offering maximum flexibility for industrial automation applications. Multiple Back Panels can be connected horizontally to support larger projects.

Eight PNP inputs are wired to the Back Panel and can be accessed on the spring loaded connectors. Inputs can read active high signals 24VAC or DC.

Like all HOP cards, the Eight MOSFETS with PWM features 18 LED indicators. The power LED blinks when power is applied and the local processor is operational. An error LED illuminates when the dedicated PANIC pin on the Back Panel terminal block is activated. Eight LEDs display the real time status of each input. Eight more LEDs show the status of the outputs.

An RS485 port enables communication with external PLCs or industrial controllers using the industry-standard MODBUS RTU protocol.

Power Requirements

The Eight MOSFETS with PWM card is powered via the Back Panel power connector.

MOSFET outputs are open drain and the load has to be powered from an external power supply. Connection to the system ground is optional, depending on your application.
The local processor is powered from the 5V rail through a 3.3V LDO regulator and consumes 10 mA.

Error Processing

One pin on the spring-loaded terminal block of the Back Panel is reserved for signaling an error condition. The user can connect this pin to an external contact of their choice. When the error signal is activated, the Eight 4-20mA Analog Outputs card automatically resets all outputs to a predefined default state.

Current Sensing Outputs

Each open-drain output is connected to ground through a 1 mΩ (high-current) or 2 mΩ (high-voltage) power resistor. The voltage drop across the resistor is measured using a differential current sense amplifier. This allows the system to calculate the power consumed by each load, limit the current, or disable the output if a predefined current threshold is exceeded.

GPIO Pinout

The optically isolated inputs are routed through the 2x20 GPIO connector to the corresponding terminal block on the Back Panel.

CUT: If the watchdog is enabled and the Raspberry Pi fails to access the I2C port within the preset time, the CUT line is activated, disconnecting power to the Raspberry Pi for 10 seconds.

SDA, SCL: I²C communication lines used for data (SDA) and clock (SCL) exchange between the Back Panel and the Raspberry Pi.

ID0-2: Stack level allocation pins. The stack level is automatically determined by the slot into which the card is inserted on the Back Panel.

INT: Interrupt line. This line can be manually triggered or programmed to interrupt the Raspberry Pi based on a specific input value or sequence.

IO18: This pin is a dry contact to ground and can be activated by an external contact wired to the Back Panel terminal block. When triggered, it resets all outputs to a predefined default states.

IO01-IO16: Eight Opto-isolated inputs: Odd-numbered inputs are routed to the positive side, and even-numbered inputs to the negative side. AC signals can be routed either way.

IO01-IO02: Input #1

IO03-IO04: Input #2

IO05-IO06: Input #3

IO07-IO08: Input #4

IO09-IO10: Input #5

IO11-IO12: Input #6

IO13-IO14: Input #7

IO15-IO16: Input #8

BACK PANEL TERMINAL BLOCK PINOUT

Eight Relays Eight Inputs Back Panel Terminal Block Connections

DOT MATRIX DISPLAY

Eight Relays Eight Inputs for Raspberry Pi Back Panel - OLED Display

The Eight MOSFETS with PWM card includes a 128 × 32 dot-matrix display driven by the on-board processor. It can show status information, self-test results, and error messages. At power up it displays the card name and the I2C address.

ELECTRICAL SPECIFICATIONS

Power Supply: 5V 10mA; 24V 120mA Back Panel provided
Source/Sync outputs: 14bit PWM
Relays 5-8: N.O. contacts 8A/48VAC/24VDC

MECHANICAL SPECIFICATIONS

Eight Relays Eight Inputs for Raspberry Pi Back Panel Mechanical

DOWNLOADS

Hardware Schematic V1.0

2D DXF Mechanical

3D STEP Model

3D Printable Enclosure

SOFTWARE

Command Line Drivers

Python Libraries

CODESYS Driver

OpenPLC Module

QUICK START

Plug the Eight MOSFETS with PWM card on the Back Panel for Raspberry Pi and power up the system.
Enable I2C communication on Raspberry Pi using raspi-config.
Install the software from github.com:

~$ git clone https://github.com/SequentMicrosystems/8mosfets1-rpi.git
~$ cd /home/pi/8mosfets1-rpi
~/8relind-rpi$ sudo make install
~/8relind-rpi$ 8mosfets1

The program will respond with a list of available commands.

FAQ

Q: What is the primary function of this card?
A: It provides eight MOSFET output channels (four high-current, four high-voltage) with PWM control and real-time current sensing. It's designed for switching and monitoring DC loads in automation, lighting, and motor control systems using the Sequent Microsystems Back Panel.

Q: What types of loads can I control with this card?
A: The card is designed to drive DC loads only, such as motors, solenoids, LEDs, and heating elements. High-current outputs support up to 12 A @ 24 V DC, while high-voltage outputs handle up to 4 A @ 48 V DC. It is not suitable for switching AC loads.

Q: How is the stack position determined?
A: Stack position is automatically assigned based on the physical slot the card occupies on the Back Panel. No DIP switches or software configuration are required.

Q: How is the RS485 port configured?
A: The RS485 port is permanently connected to the shared RS485 bus on the Back Panel. It is managed by the onboard processor and supports MODBUS RTU slave communication. The Raspberry Pi does not directly control the RS485 signals on this card.

Q: How is current sensing implemented?
A: Each output is grounded through a precision low-value resistor (1 mΩ or 2 mΩ), and the voltage drop is measured using a differential amplifier. This allows the system to monitor load current, calculate power, and enforce current limits by shutting off outputs when thresholds are exceeded.

Q: Can I use PWM on all outputs?
A: Yes, all eight outputs support software-controlled PWM at 1 kHz, enabling fine-grained control of load power such as motor speed or LED brightness.

Q: Can the card operate without a Raspberry Pi?
A: Yes. When connected via RS485, the onboard processor allows the card to function as a MODBUS RTU slave, making it controllable by any MODBUS-compatible PLC or controller.

Q: Is the card software-compatible with other Sequent MOSFET products?
A: Yes. It uses the same command-line tools and open-source libraries as other Sequent Microsystems cards, including Python and C APIs.

Q: How is the card powered?
A: The card accepts 5 V or 10–24 V DC through the Back Panel. An onboard regulator supplies up to 3.3V  to the local processor.

Q: What happens if a load exceeds the current limit?
A: The card can automatically disable the affected output when current exceeds a user-defined threshold, protecting the load and the system.

Q: Where can I find documentation and examples?
A: Visit Sequent Microsystems’ GitHub repository for open-source code, wiring diagrams, and setup instructions:
👉 https://github.com/SequentMicrosystems