Issue:
Comm5 (LonTalk) Wiring Guidelines
Resolution:
Refer to Trane recommended wire for Comm3, Comm4, Comm5 (LonTalk), and BACnet MS/TP links for details on Trane approved wire.
Here are some bulleted items from the Comm5 wiring installation guide BAS-SVN01A-EN with additional comments and clarifications:
Use 22 AWG Level 4 unshielded communication wire for most LonTalk installations. This pertains to:
The LonTalk link on the Tracer Summit BCU.
The LonTalk links on the Tracer SC.
The LonTalk link on the Tracer Loop Controller.
Shielded wire is required for Comm4 communication links. This pertains to:
The Comm4 link(s) on the Tracer Summit BCU.
The Comm4 link on the VariTrac II and III Central Control Panel (CCP).
A continuous shield is required when shielded wire is used. At each controller, splice shield wire and tape back to prevent grounding. Connect shield wire to earth ground at system panel and repeater.
For Tracker BMTK / VariTrac III Central Control Panel (CCP) installations, there are two wiring options to consider:
Use 22 AWG shielded Level 4 wire for all communication wiring (which includes the LonTalk link from the Tracker to the VariTrac III CCP and other LonTalk controllers, and the Comm4 link from the VariTrac III CCP to the Comm4 VariTrac or VariTrane UCMs). This option allows one type of wire to be used for the entire installation.
Use 22 AWG unshielded Level 4 wire for LonTalk communications and 18 AWG shielded (Trane "purple") for Comm4 communications.
Refer to What type of wire is recommended for Tracker BMTK or VariTrac III CCP communication links? for additional details.
Limit LonTalk links to 4,500 ft and 60 devices maximum (without a repeater).
Use the following termination resistors on all LonTalk links:
105 ohms at each end for 22 AWG Level 4 (unshielded or shielded) wire
82 ohms at each end for 18 AWG Trane "purple" wire
Use daisy chain topology.
Limit zone sensor communication stubs to 8 per link, 50 ft each maximum.
Use one repeater for an additional 4500 ft, 60 devices, and 8 communication stubs.
Notes:
Could you use 18 AWG shielded (Trane "purple") wire for LonTalk wire? We discourage this, but the answer is yes (people usually don't consider this option because it is more expensive). Furthermore, it would be unwise to do so since Echelon has not specified an 18 AWG cable that can be used with their free topology transceivers (like the FTT-10A).
Could you use 22 AWG shielded wire for Comm4 communications? The answer is yes, but only as an alternative for the Comm4 link from the VariTrac III CCP to the Comm4 VariTrac or VariTrane UCMs. On Tracer Summit installations, use 18 AWG shielded (Trane "purple") wire for all Comm4 communications.
Changes:
Other Question/Problem/Cause Statements:
- Document: Comm5 Wiring Installation (BAS-SVN01A-EN, June 2003)
- LonTalk wiring and topology recommendations
- LonTalk wiring requirements
- Termination resistance placement for LonTalk links
- LonTalk physical link repeater: Requirements, guidelines, and connections
- LonTalk zone sensor comm jack
- Zone sensor communication stubs
- Specifications for Level 4-compliant cables
- How should the comm link shield be handled?
- Do I run a shield with Comm5 wire?
- Should I use shielded or unshielded wiring for Comm5?
- Is there a Comm5 (LonTalk) wiring guide?
- Do I use 18 or 22 AWG for Comm5 wiring?
- What is the maximum length for a Comm5 (LonTalk) Link?
Facts:
- Miscellaneous BAS/ICS
- Tracer Loop Controller (TLC)
- Tracer Summit Building Control Unit (BCU)
- Tracker BMTK
- CSC LCI-I
- Intellipak LCI-I
- Chiller LCI-C
- Tracer AH540/541
- Tracer MP501
- Tracer MP503
- Tracer MP580/581
- Tracer SC
- Tracer VM512
- Tracer VV550/551
- Tracer ZN510/511
- Tracer ZN517
- Tracer ZN520/521
- Tracer ZN523
- Tracer ZN524
- Axiom WS Comfort Systems (GECA, GEHA, GERA, GEVA)
- Horizontal Unit Vents (HUVC)
- Vertical Stack (GETA)
- Vertical Unit Ventilators (VUVC)
- WS Hi-Efficiency Horizontal (WPHF)
Original wave: wave1791