Bryant 548J Service And Maintenance Instructions page 41

on manufacturer. Protocols do not change the function of
a controller; just make the front end user different.
The RTU- - MP can be set to communicate on four different
protocols: BACnet, Modbus, N2, and LonWorks. Switch 3
(SW3) on the board is used to set protocol and baud rate.
Switches 1 and 2 (SW1 and SW2) are used to set the
board's network address. See Fig. 63 for the switch setting
per protocol. The 3rd party connection to the RTU- - MP is
through plug J19.
NOTE: Power must be cycled after changing the SW1- - 3
switch settings.
BACnet MS/TP
BACnet Master Slave/Token Passing (MS/TP) is used for
communicating BACnet
BACnet- - only controllers. This is the default Bryant
communications protocol. Each RTU- - MP module acts as
an MS/TP Master. The speed of an MS/TP network can
range from 9600 to 76.8K baud. Physical Addresses can
be set from 01 to 99.
Modbus
The RTU- - MP module can speak the Modicon Modbus
RTU Protocol as described in the Modicon Modbus
Protocol Reference Guide, PI- - MBUS- - 300 Rev. J. The
speed of a Modbus network can range from 9600 to 76.8K
baud. Physical Addresses can be set from 01 to 99.
Johnson N2
N2 is not a standard protocol, but one that was created by
Johnson Controls, Inc. that has been made open and
available to the public. The speed of N2 network is
limited to only 9600 baud. Physical addresses can be set
from 01 to 99.
LonWorks
LonWorks is an open protocol that requires the use of
Echelon's Neuron microprocessor to encode and decode
PROTOCOL DS8
BACnet MS/TP
Unused
(Master)
Modbus
Unused
(Slave)
N2
Unused
(Slave)
LonWorks Unused
NOTE:
DS = Dip Switch
BACnet MS/TP SW3 example shown
Baud Rate Selections
BAUD RATE
9600
19,200
38,400
76,800
over a sub- - network of
SW3 Protocol Selection
DS7 DS6
OFF OFF
OFF OFF
OFF OFF
ON ON
DS2 DS1
OFF OFF
ON OFF
OFF ON
ON ON
Fig. 63 - - RTU- - MP SW3 Dip Switch Settings
the LonWorks packets. In order to reduce the cost of
adding that hardware on every module, a separate
LonWorks Option Card (LON- - OC) was designed to
connect to the RTU- - MP.
This accessory card is needed for LonWorks and has to be
ordered and connected using the ribbon cable to plug J15.
The RTU- - MP's baud rate must be set to 38.4k to
communicate with the LON- - OC. The address switches
(SW1 & SW2) are not used with LonWorks.
Local Access
6
BACview Handheld
6
The BACview is a keypad/display interface used to
connect to the RTU- - MP to access the control information,
read sensor values, and test the RTU, see Fig. 64. This is
an accessory interface that does not come with the MP
controller and can only be used at the unit. Connect the
6
BACview to the RTU- - MP's J12 local access port. There
are 2 password protected levels in the display (User and
Admin). The user password is defaulted to 0000 but can
be changed. The Admin password is 1111 and cannot be
changed. There is a 10 minute auto logout if a screen is left
idle. Contact your Bryant applications engineer for details
on navigation and screen content.
Virtual BACview
Virtual BACview is a freeware computer program that
functions as the BACview
interface (USB- - L) is required to connect a computer to
the RTU- - MP board. The link cable connects a USB port
to the J12 local access port. This program functions and
operates identical to the handheld.
DS5 DS4 DS3
OFF ON OFF
ON ON OFF
OFF ON ON
OFF ON OFF
41
6
Handheld. The USB Link
DS2 DS1
Select Baud Select Baud
Select Baud Select Baud
OFF OFF
OFF OFF
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