Product Overview
Trane Comm3/4 Communications Bridge for Tracer SC+ – Unused, New Old Stock
This listing covers a Trane BMTB-series Comm3/4 Communications Bridge engineered to bring legacy Trane Comm3 and Comm4 unit controllers into a Tracer SC+ BACnet/IP building automation system.
Trane designed this bridge as a precise link between older field buses and the SC+ supervisory layer, allowing decades-old rooftop, VAV, or unit controllers to coexist cleanly with modern BACnet/IP workflows. Its job is simple but critical: translate legacy Trane control traffic into SC+ objects that look and behave like native BACnet equipment.
Product Condition
Unused, new old stock. Sourced from a warehouse clearing out legacy Trane replacement inventory. One terminal block screw is missing on a connection point; photos will show the location. No other issues were noted. Unit shows typical minor handling from long-term shelf storage, with no indication of operational compromise.
Product Overview
The Trane Comm3/4 Bridge (BMTB family) serves as the protocol conversion layer between existing Comm3/4 trunks and a Tracer SC+. Once installed, it presents legacy Trane controllers to SC+ as BACnet/IP objects, allowing trending, alarming, graphics, and equipment navigation through Synchrony as though the older units were native BACnet hardware. SC+ then exposes this data to third-party BACnet/IP clients as needed.
In operation, the bridge behaves conceptually like a miniature BCU: it aggregates Comm3/4 sub-devices behind a single BACnet entry point, streamlining discovery and reducing engineering overhead.
Key Features
- Interfaces Trane Comm3 and Comm4 communicating controllers with Tracer SC+.
- Provides protocol translation from legacy Tracer networks into BACnet/IP objects.
- Auto-installs supported legacy devices inside SC+ for standard graphics and navigation.
- Routes alarms from Comm3/4 controllers through SC+ for centralized acknowledgment and history.
- Allows legacy controllers to participate in SC+ application libraries and sequences.
- Supports up to the SC+ system-wide limit of approximately 240 total Comm3/4 devices via multiple bridges.
- Behaves as a BACnet device representing its Comm3/4 sub-devices to SC+ and third-party systems.
- BMTB-series design cited in Trane documentation and field integration notes.
- Suitable for migration scenarios replacing Summit/BCU front ends with SC+.
Applications
- Integrating existing Trane Comm3/4 unit controllers during SC+ upgrades.
- Modernizing legacy Trane rooftop or VAV systems without replacing field devices.
- Bringing older Trane control networks into BACnet/IP analytics platforms.
- Supporting building-wide migrations away from Summit or BCU architectures.
- Mixed-protocol SC+ deployments combining BACnet/IP, MS/TP, LonTalk, Modbus, and Comm3/4.
- Engineering retrofit designs where legacy equipment must remain in service.
- Providing BACnet-accessible legacy data to external supervisory software.
Frequently Asked Questions
Does the missing terminal screw affect functionality?
The missing screw is located on one terminal block position and is shown in the listing photos. The terminal can be used with a replacement screw of the appropriate size; the condition does not affect the electronics of the module.
Can this bridge be used as a standalone Comm3/4 to BACnet converter?
No. It is designed to operate with a Trane Tracer SC+ controller. The SC+ performs BACnet/IP presentation and manages legacy device installation.
How many Comm3/4 devices can be supported?
SC+ supports up to roughly 240 total Comm3/4 devices across one or more bridges. Practical limits depend on overall SC+ system design and device counts.
Does the unit require Trane licensing?
Typical deployments require proper SC+ licensing and configuration. Integrators should verify site requirements in Trane’s installation and operations manuals.
Is this compatible with newer Trane replacement solutions?
Trane has indicated that future hardware will replace the existing Comm3/4 Bridge family. This module remains appropriate as a service replacement in legacy SC+ environments.
This bridge spent its life waiting on a shelf while buildings around it modernized; now it’s ready to bring older Trane controllers forward into a BACnet/IP world. The next chapter of that upgrade path is yours to determine.
