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What’s the Value of Universal Inputs and Outputs (I/O)?


When Computrols began manufacturing in the early 90s, we made a conscious decision from day one, to always include true universal inputs and outputs on our flagship parent-level control boards. The way our founders saw it, if we chose to restrict the total number of points to a combination of binary and analog-only points, we would ham-string our technicians, distribution partners, and customers that strive to be self-performers.

What are AI, AO, BI, and BO?

Most points in a building automation system can be classified as one of the following:

  • Analog Input (AI)
    • Used to measure temperature, resistance, voltage, or current
  • Analog Output (AO)
    • Used to control dampers, valves, VFDs, actuators, etc.
  • Binary Input (BI)
    • Used for differential pressure switches, auxiliary contacts, etc.
  • Binary Output (BO)
    • Used for pilot relays for general two-position control
Universal Inputs and Outputs

The most important difference between analog and binary points is that analog points can represent a range of values where binary can only represent 2 different states (typically off/on).

The difference between an input and an output is an input brings data from an end device back to your BAS whereas an output will control an end device.

Most DDC controllers on the market today limit each point to one of these 4 variations. Those that do offer universal inputs and outputs typically achieve this by using manual dip switches and jumpers on the controller that offer some degree of flexibility.

What Makes Computrols Different?

Computrols has been providing universal I/O, also known as 4-in-1 points, on our parent-level controllers for nearly 30 years…but why?

The answer can be found in our core values of Quality and Simplicity. While we could certainly produce a cheaper controller with dedicated I/O, we know that this would put an additional burden on our team members, customers, and distribution partners.

Computrols CEO, Drew Mire explains, When it comes to universal I/O on our controllers, it’s just another example of Computrols refusing to cut corners. Our ownership having field experience is invaluable when it comes to features like this. They know how it feels when you have I/O available but it doesn’t match up with the device you are looking to add to your system.”

The Benefits of Universal I/O

The primary benefit of this feature is flexibility. Rather than making controllers for specific pieces of equipment with a specific number of AI, AO, BI, and BO, Computrols LX Controller gives users the ability to program any piece of equipment on any point of the controller. Points are software configurable which means no dip switches or jumpers are required to change the point selection in the field. Everything is automatically configured in CBAS when you select your desired point type.

Universal i.o. 1

With the LX controller line, you also get the benefit of Wire Check, our on-board wiring fault detection circuitry which can alert you to out of range or failed end devices. 

This not only affords you the opportunity to use any remaining open points you have on existing controllers in the field, but it also makes engineering a new job as simple as knowing your hardware point counts in each cabinet location.

Real-World Use, Real-World Value

Our customers’ and partners’ input is invaluable in helping shape our products and the LX Controller along with its universal points is no different.

James Williams of Williams Mechanical Services elaborates, “The controllers are designed around the end-user, not the manufacturer! Universal I/O is a remarkable feature. We are able to quickly engineer projects and turn around proposals to our customers faster than ever. Computrols is the only manufacturer in the industry that has the labeling on the control boards. The universal I/O feature gives you the option to use Computrols as part of the solution to any problems that we encounter in the real world!”

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