Adjusting Bacnet Ms/Tp Properties Using An Equipment Touch - United Technologies Carrier Unit Vent Open Integration Manual

Connect the communications wiring to the Comm port in the screw terminals labeled Net +, Net -, and Shield.
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Wire specifications
A dedicated 22 AWG shielded twisted pair wire (EIA 485)
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Maximum wire length 2000 feet (610 meters) or 32 nodes
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Devices should be daisy-chained and not star-wired
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Attach the drain/shield wire to both ends of the network segment and through every controller
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NOTE Use the same polarity throughout the network segment.
Turn on the power for the Unit Vent by connecting power terminals.
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Adjusting BACnet MS/TP properties using an Equipment Touch

You may need to adjust the following BACnet MS/TP protocol timing settings using the Equipment Touch.
Max Masters - defines the highest MS/TP Master MAC address on the MS/TP network.
For example, if there are 3 master nodes on an MS/TP network, and their MAC addresses are 1, 8, and 16, then
Max Masters would be set to 16 (since this is the highest MS/TP MAC address on the network).
This property optimizes MS/TP network communications by preventing token passes and "poll for master"
requests to non-existent Master nodes.
In the above example, MAC address 16 knows to pass the token back to MAC address 1, instead of counting up to
MAC address 127. Each MS/TP master node on the network must have their Max Masters set to this same value.
The default is 127.
Max Info Frames - defines the maximum number of responses that will be sent when the Unit Vent receives the
token. The default is 10 and should be ideal for the majority of applications. In cases where the Unit Vent is the
target of many requests, this number could be increased as high as 100 or 200.
NOTES
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BACnet MS/TP networks can be comprised of both master and slave nodes. Valid MAC addresses for master
nodes are 0 – 127 and valid addresses for Slave nodes are 0 - 254.
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If the third party attempts to communicate to the controller but does not get a response, make sure the
controller is set as a BACnet MS/TP (m) master. The BACnet software asks the controllers, "Who Is?" This is
to auto-locate devices on the network. Only controllers set as masters will answer this request.

See Appendix A (page 26) for Network Points List.

See Appendix B (page 35) for the BACnet Protocol Implementation Conformance Statement (PICS).
Unit Ventilator
Integration Guide
5
Communications wiring
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