Using BACnet® Compatible RIB® Relays

Tech Tuesday Using BACnet® Compatible RIB® Relays

Building automation controllers can be quite expensive, and purchasing one just to add a couple more points on the network may not be ideal. Luckily Functional Devices has a solution for these cases – using BACnet® compatible RIB® Relays!

Our selection of BACnet® MS/TP Network RIB® Relays can be powered from 24Vac/dc up to 277Vac. They all use standard BACnet® objects: binary input, binary output, analog input, analog output, accumulator and device. The PIC Statements, available for download on our website, indicate which objects each model uses.

Available Models

  • Relays
  • Relay & current sensor combinations
  • Thermistor input
  • Analog input
  • Analog output

Technical Specifications

  • Local MS/TP Address setting
  • Local Baud Rate setting
  • Local relay override
  • Each device is 1/8th unit load
  • Jumper to connect integral end-of-line (EOL) resistor
  • Certified by the BACnet® Testing Lab (BTL)

Answers to Frequently Asked Questions

Since these devices can be more complicated than a traditional RIB®, we tend to get more support questions about them. The following are answers to common questions:

  • If the Baud Rate or MS/TP Address for the device is changed, power must be cycled to the device for the changes to be realized.
  • An EOL jumper should only be used if the device is at the end of the trunk.
  • 22-24 AWG shielded, twisted pair cabling is recommended.
  • When connecting 24 Vac to both the RIB® and a half-wave device, damage can occur. To prevent this, you can:
    • Option 1: Use separate transformers for each device
    • Option 2: Add diode between devices:

BACnet® compatible RIB® Relay RIBTW2401B-BC

  • The last point I want to make relates to the Device ID for a BACnet® RIB® device. The Device ID will default to 277XXX, where XXX is the MS/TP address set on the device DIP switches. This ID can be changed by writing to the Object Identifier Property of the Device Object. The way to do so is slightly different for each controller, so give us a call if you are having troubles doing so.

If you still have questions about our BACnet compatible RIB® relays, feel free to send us an email or give us a call, and we’ll be happy to help!

Henry Smith
Henry Smith

Henry Smith is the Product Design Manager at Functional Devices, Inc. He has a BS in EET obtained from Purdue University in 2014 and a lifelong interest in electronics. As an engineer at Functional Devices, he gets to provide Technical Support to our customers, from distributors to specifying engineers and installers.

Henry enjoys providing tech support, as it allows our company to assist at every level of our product’s lifecycle and exposes us to interesting and unique applications. While not every technical question is unique, even answering a simple question or providing someone with the information in a timely manner can go a long way to helping them meet a deadline.

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