Distech Controls ECLYPSE APEX, Руководство пользователя

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116 ECLYPSE APEX
Product Typical Data Bus Connection Terminals
Inverting Non-inverting Reference
Distech ECB Series Controllers NET – NET + 24V COM
ECB-PTU Series Line-Powered Controllers NET – NET + COM
ECLYPSE Series Controllers NET – NET + S
Thermostat – + Ref
Repeater
Data–
Data1–
Data+
Data1+
N/A
BACnet/IP to MS/TP Adapter RT– RT+ COM
BACnet/IP to MS/TP Router – + SC
Table 9: Common Identification Labels for BACnet MS/TP Data Bus Polarity for Distech Controls’ Products
Except for a Distech ECB-PTU Line-Powered Controllers and ECY Series Controllers, never connect the shield of the
BACnet MS/TP data bus to the Reference terminal. See
Data Bus Shield Grounding Requirements .
Device Manufacturer Typical Data Bus Connection Terminals
Inverting Non-inverting Reference
Common identification labels for BACnet MS/TP data bus
polarity by other Manufacturers
B A SC
– + G
TxD–/RxD– TxD+/RxD+ GND
U– U+ COM
RT– RT+ REF
Sig– Sig+ S
Data– Data+
Table 10: Common Identification Labels for BACnet MS/TP Data Bus Polarity for other Manufacturers
When interfacing with BACnet MS/TP devices from other manufacturers, refer to the documentation provided with the
device to correctly wire the device.
Maximum Number of BACnet MS/TP Devices on a Data
Bus Segment and Baud Rate
The following technical parameters limit the number of devices on a BACnet MS/TP Data Bus Seg-
ment.
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The BACnet MS/TP Data Bus Segment has a hard limit on the number of devices that can com-
municate due to the device addressing scheme (the MAC Address Range for BACnet MS/TP De-
vices). See
Data Bus Segment MAC Address Range for BACnet MS/TP Devices .
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Each device presents an electrical load on the BACnet MS/TP Data Bus Segment. This is called
device loading. The number of devices that can be connected to a BACnet MS/TP Data Bus Seg-
ment is limited by the loading of each device. See
Device Loading .
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Choosing a low baud rate can cause BACnet MS/TP Data Bus congestion that can limit the
amount of data that can be efficiently exchanged between devices connected to the BACnet MS/
TP Data Bus. For example, at 9600 baud, the maximum number of devices is reduced to 25 due to
the increased time it takes for token passing between devices. The recommended baud rate is 38
400. See
Baud Rate .
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Distech Controls recommends that you connect no more than 50 of our ⅛ or ½-load devices on a
single BACnet MS/TP Data Bus Segment when a baud rate of 19 200 or higher is used (preferably
38 400 baud). This is to ensure that the BACnet MS/TP Data Bus has enough bandwidth to effi-
ciently communicate network variables between controllers.
BACnet MS/TP Communication Data Bus Fundamentals