Automation Components, Inc.
2305 Pleasant View Road | Middleton, WI 53562
Phone:
1-888-967-5224 |
Website:
workaci.com
Page 3
Version: 8.0
I0000668
BACnet MS/TP INTERFACE
(Continued)
ACI recommends using Belden 9841 or compatible
cable for RS-485 communication wiring. If the
MOD9200BNT is the only device on the RS-485 bus or
if it is the last device on the bus, wire the left set of
“A&B” terminals - see
FIGURE 4
(top). If the
MOD9200BNT is in the middle of the bus and needs to
be daisy chained, both sets of “A” and “B” terminals
must be used: the left set for incoming wiring, and the
right set for outgoing - see
FIGURE 5
(middle). Be
mindful of wire polarity and termination.
Tie the shield wires together using a wire nut and do
not terminate the shield wire in the shield terminal
block. The shield wire is to be grounded at the
controller end only. Do not terminate the shield wire in
the shield terminal block. Do not use “Star” or “T” wiring.
The MOD9200BNT has a dip switch selectable 120 ohm
end-of line resistor built into the BACnet proto node. It
is marked SW2 and is set to default “Off”. The resistor
can be turned “On” if the MOD9200BNT is the last
device on the bus - see
FIGURE 6
(bottom).
CONFIGURATION OF TRANSCEIVER
The sensors need to be configured to the MOD9200BNT
using the configuration program (included), a laptop,
and a crossover cable. Refer to the user manual for
programming, baud rates, node ID, and downloading
program to the transceiver.
FIGURE 4:
STAND ALONE
BAUD SWITCHES
120 OHM TERMINATION
RESISTOR SWITCH
SW4
SW2
ON
SW3
NODE ID SWITCHES
GROUND AT
CONTROLLER ONLY
SHIELD CLIPPED
IN
A+
B- SHLD A+
B-
GROUND AT
CONTROLLER ONLY
SHIELD
IN
OUT
A+
B- SHLD A+
B-
FIGURE 5:
DAISY CHAIN WIRING
FIGURE 6:
PROTOCESSOR 3.0
TROUBLESHOOTING
PROBLEM
Can’t Discover
MOD9200BNT:
SOLUTION(S)
•
Is baud rate on transceiver and the
com bus the same?
•
Check for duplicate node ID
•
Is Max Master set to 127?
•
Check wiring and wire polarity at
RS485 terminals
