Modern building automation systems (BAS) are expected to do more with fewer controllers. As facilities add new equipment, zones, and energy-saving strategies, the need to expand input/output capacity and sequence loads becomes essential. That’s where I/O expanders and sequencers come in.
Functional Devices has been a trusted leader in reliable, installer-friendly building automation components for decades, helping contractors and integrators streamline projects and improve performance. If you’re looking for ways to add capacity or simplify sequencing in your BAS, the RIBMN24Q4C-PX is designed to deliver. Contact Functional Devices today to see how our solutions can support your BAS.
In this blog, we’ll explore what I/O expanders and sequencers are, how the RIBMN24Q4C-PX works, and why it’s the smart choice for HVAC, lighting, and other building automation applications.
What Are I/O Expanders and Sequencers?
An I/O expander increases the number of inputs or outputs available to your existing building automation controller. Instead of replacing a controller with a larger one, you simply add an expander to handle more zones or devices. This is particularly valuable when adding sensors, relays, or equipment to an existing BAS.
A sequencer stages loads on or off in a timed order. This function is critical for systems like HVAC or pumps, where simultaneous starting can cause current surges or mechanical stress. Sequencing ensures equipment starts and stops smoothly, extending equipment life and reducing energy spikes.
By combining both functions, the RIBMN24Q Series provides a flexible and scalable solution for a wide variety of building automation needs.
The RIBMN24Q4C-PX
The RIBMN24Q4C-PX is part of our RIBMN Series of multi-relay I/O expanders and sequencers. This model essentially gives you four relays in one compact unit, reducing the number of separate components needed in your panel.
Features
Here are the main specs:
- 0-10Vdc Analog Input Control
- Four (4) SPDT 15A relays
- Real-time Analog Input Voltage Display
- Programmable On/Off Settings
- Heartbeat Indicator
The RIBMN24Q4C-PX has an on-board voltmeter tied directly to the Analog Input. At any time, a button can be pressed to display the real-time voltage on the Input.
This device has field-programmable ON and OFF voltages. Each relay works independently from the others and can be turned ON anywhere between 0.5Vdc and 10Vdc. Also, each relay's OFF point can be set anywhere below the ON voltage.
Key Benefits for BAS Applications
Those features translate into benefits, including:
- Scalable Control. Add I/O capacity without needing an entirely new controller.
- Simplified Sequencing. Built-in sequencing helps protect equipment and improve energy efficiency.
- Flexible Integration. Works seamlessly with HVAC, lighting, and other building automation systems.
- Faster Installation. Prewired, labeled terminals mean less time on site and fewer wiring mistakes.
Each of the four relays on-board are rated up to 15A @ 120V or 10A @ 277V individually. That means there is no need to have another relay from the control board to the load; the control board can handle the load directly.
Typical Use Cases
The RIBMN24Q4C-PX could be used in many applications, like with a 0-10Vdc thermostat in a multi-stage heating application or with a controller to stage multiple pumps or fans. The possibilities are not endless, but there are quite a few. Here are ideal use cases:
- Coordinating fan or pump stages
- Sequencing lighting banks to avoid power spikes
- Expanding relay capacity for air handling units, chillers, or boilers
- Integrating additional load control points into existing BAS without reprogramming
FAQs About the RIBMN24Q4C-PX
Q: What is the RIBMN24Q4C-PX?
A: The RIBMN24Q4C-PX is a multi-relay control module designed to expand inputs and outputs in building automation systems. It combines four independent relays into one compact unit for flexible control of HVAC, lighting, or other building loads.
Q: How many relays does it have?
A: It includes four SPDT (Form C) relays, each with its own common, normally open, and normally closed contacts for versatile wiring options.
Q: What makes this model different?
A: Unlike standard relay modules, the RIBMN24Q4C-PX features field-programmable ON/OFF voltages and 0–10Vdc input capability, making it ideal for staging equipment or interfacing with BMS controllers and thermostats.
Q: What applications is it best for?
A: It’s commonly used for sequencing pumps, fans, or multi-stage heating/cooling systems, and for expanding control in energy-management projects.
Q: Does it reduce installation time?
A: Yes. By consolidating multiple relays in one enclosure and handling significant loads directly, it minimizes panel clutter and eliminates the need for intermediary relays.
Expanding Your Building Automation Systems with Building Control Relays
The RIBMN24Q4C-PX makes expanding your building automation system simple by combining multiple independent relays, field-programmable voltages, and high load capacity into one compact unit. It’s ideal for staging pumps, fans, multi-stage heating equipment, and more—helping you save install time, reduce panel clutter, and improve overall system efficiency.
Whether you’re upgrading an existing facility or designing a new system, the RIBMN24Q4C-PX delivers reliable, flexible control that scales with your needs. Contact Functional Devices today to learn how this model can simplify your next BAS project.