Specifications

Table 2: BACnet Router Attributes
User Action or Recommended
Setting
DescriptionBACnet Router Attribute Name
default=0The MS/TP MAC address of the BACnet
Router you select must not conflict with
any other MS/TP device on the same wire.
Address zero (0) is generally
recommended. For other field devices
connected to the same RS-485 MS/TP
bus, use sequential addressing following
the Metasys MS/TP bus addressing
recommendations and reserved
addresses. No single MS/TP MAC address
can be used by more than one device on
the same MS/TP bus regardless of the
type of device.
MS/TP MAC Address
38400The RS-485 connection on the BACnet
Router requires a specified baud rate in
order to initiate communication with field
devices that may use auto-baud rate
configuration.
Baud Rate
127The highest master MS/TP node number
used on the bus.
MS/TP Max Master
80 to 100 (all devices are
Johnson Controls field devices)
or
20 (some or all devices are third-party field
devices)
The Max Info Frames setting on the
BACnet Router you specify should be high
enough to allow the transmission of at
least as many MS/TP frame packets as
there are available MS/TP frame buffers
in the router.
MS/TP Max Info Frames
480
(or use default)
The maximum size of a BACnet APDU
(Application Layer Protocol Data Unit)
accepted by the device. For most BACnet
Routers, this is a read-only attribute that
is fixed to the maximum value defined for
BACnet MS/TP.
Max APDU Length
To protect from intruders, change the
default password.
A password that you must enter to access
the BACnet Router configuration settings.
Router Configuration Password (if
available)
Set these appropriately for the site and
the router.
The BACnet Router requires common IP
communication configuration settings for
the UDP port (default 47808), IP network,
and IP subnet mask.
IP settings
11MS/TP Communications Bus Technical Bulletin