Distech ECYPSE User Manual

BACnet MS/TP Communication Data Bus Fundamentals
ECLYPSE User Guide 125
Device Addressing
Device addressing allows the coordinated transfer of messages between the intended
devices on the BACnet MS/TP data bus and with devices connected to the internetwork. For
this, each device connected to the BACnet MS/TP data bus is identified by a MAC address,
a Device Instance number, and a Network Number:
 The MAC Address uniquely identifies a device on a Network (identified by a Network
Number). Devices on another Network can have the same MAC Address as messages
are not passed at the internetwork level using the MAC Address. The MAC Address also
defines the devices on the data bus that are Masters and Slaves, among other
categories (see Table 11-7). The MAC Address is also used to share data bus
bandwidth between devices through token passing between Master devices.
 The Device Instance uniquely identifies a device across the BACnet internetwork. The
Device Instance is any number between 0 and 4 194 303. It is with the Device Instance
that messages are exchanged between BACnet devices. The Device Instance is also
used by routers to forward messages to devices located elsewhere in the internetwork.
Unlike a MAC Address, a Device Instance cannot be reused elsewhere in the BACnet
internetwork (it must be unique for the entire network).
 The Network Number is any number between 1 and 65 534. A network number identifies
a LAN for routing purposes.
Both the MAC Address and the Device Instance must be set for each device and are
essential for proper BACnet LAN operation.
For an example of how MAC address, Device Instance number, and Network Number apply
to a typical BACnet network, see Figure 11-16.
About the MAC Address
The MAC Address is a number from 0 to 255; however we recommend reserving some MAC
Addresses for common commissioning and maintenance tasks. For example, when a
portable adaptor is set to use one of these reserved MAC Addresses, it can be temporarily
connected with certainty to any BACnet MS/TP data bus of any site without conflicting with
other devices already connected to the BACnet MS/TP data bus. We strongly recommend
that the MAC address of ECY Series Controller’s MS/TP port be always set to 0.
MAC Addresses should be used as shown in the following table.
Table 11-7: Recommended BACnet MS/TP Bus MAC Address Values / Ranges for
BACnet MS/TP Data Bus Devices
MAC Address
Value / Range
Usage
Devices
0
Data Bus Master
(ECY Series
Controller)
This address is invalid for Distech Controls’
ECB series devices
1
Temporary
commissioning
connection
Portable adaptor MAC Address for a
temporary commissioning and maintenance
connection
2
Reserved
Other
3-127
Master Range
Master devices: All Distech Controls’ devices
are master devices and should be in this MAC
Address range
128-254
Slave Range
Slave devices and network sensors
255
Broadcast
Do not apply address 255 to any device

Distech ECYPSE Specifications

General

Brand	Distech
Model	ECYPSE
Category	Controller
Language	English