1-8
AspectFT-Matrix MAX Area Controller Installation Guide (1/05/2015)
1.4.2 EIA-485 N
ETWORK
The EIA-485 network ports are used to accommodate serial network protocols that utilize two-wire,
shielded-twisted pair cabling - such as BACnet MS/TP, American Auto-Matrix PUP, and Modbus RTU.
Terminals for EIA-485 network connections are located on the left side of the controller board and are
labeled
J2
and
J3
. Each terminal has a connection for Network Positive (
N+
), Network Negative (
N-
), and
Signal Ground Reference Wire (
SG,
commonly used for serial networks that utilize a reference wire for
electrical stability).
The Matrix Area Controller should be installed at an electrical end of the EIA-485 network. Avoid network
topologies where the network is “t-tapped” or “starred”.
1.4.2.1 C
ONNECTING
EIA-485 N
ETWORKS
Connect the serial network to the determined EIA-485 port. Be sure to maintain network polarity at all
times. Failure to do so can result in loss of network communications. For protection against ground loops
or noise, connect the drain wire of the 485 network wire to a reliable earth ground.
N+
N-
Figure 1-8 MS/TP Network Connection
1.4.2.2 N
ETWORK
T
ERMINATION
AND
B
IASING
Adjacent to each EIA-485 port is a two-position switch block, which applies termination and biasing to your
485 network. To enable either termination (
TERM
) or biasing (
BIAS
), configure the respective switch
towards the ON (Up) position.
When applying termination, be certain that it is applied at both ends of your EIA-485 network at the two
end devices. In termination applications, biasing should also be enabled to ensure proper idle state
voltage.
TERM BIAS
SW2
Figure 1-9 Termination and Biasing Switches and LED Indicators