Specifications

Product Description
10
2.8 ARCnet Communication Enhancement Devices
In SiteScan Web systems, ARCnet, or ARC156, is the standard for module-to-module communica-
tions. Formerly, this was termed CMnet in SiteScan 2000/2W systems. The main difference is the con-
trol module network now operates at a faster baud rate (156K baud with ARCnet vs. 9600 or 38.4K
baud with CMnet). The increase in speed requires a low impedance / low capacitance wiring. Also, all
control modules must be wired in a daisy-chain configuration.
ARCnet enhancement devices can be used to control and maintain the proper biasing of the ARCnet
network.
2.8.1 ARC156-KIT - ARCnet Kit
The ARC156-Kit contains a PROT485 surge protection board and a DIAG485 diagnostic board within
the same site enclosure. This kit must be installed near the midpoint of each ARCnet segment.
Requires 24VAC supply (not included).
2.8.2 Other ARCnet Parts
ARCDIAG485 - ARCnet156 Diagnostics Board
The ARCnet156 diagnostics board in an enclosure provides visual indication of signal levels and adds
bias to reduce the effect of noise on a segment. More than one DIAG485 can be installed on a specific
ARCnet segment.
ARCDIAG485WO - ARCnet156 Diagnostics Board Without Enclosure
The ARCnet156 Diagnostics Board is available without an enclosure. Requires 24VAC supply (not
included).
ARCPROT485 - ARCnet156 Surge Protection Board
The ARCPROT485 is an ARCnet device used for surge suppression. It is recommended that this
device be installed at every entrance and exit of a building.
ARCPROT485WO - ARCnet156 Surge Protection Board Without Enclosure
The ARCnet156 surge suppressor device is available without enclosure.
ARCREP485 - ARCnet156 Repeater Board (Signal Booster)
The ARCnet156 Repeater boosts the ARCnet156 network signals and extends the length of the net-
work by joining one segment to another for EIA-485 networks running from 1200 bps to 156 Kbps.
Requires 24VAC supply (not included).
When designing your system, factor in the maximum wiring distance of 2,000 ft. (610m) per segment.
(A segment is up to 32 modules.) If your system requires more than 32 modules per segment or
exceeds the distance of 2,000 ft. (610m), install another gateway or, possibly, use an ARCREP485.
The signal becomes weaker as distance increases.
ARCREP485WO - ARCnet156 Repeater Board Without Enclosure
The ARCnet156 signal booster (repeater) is available without enclosure.
NOTE
Only one DIAG485 within an ARCnet segment should have its bias jumper in place.
NOTE
Install one 120 ohm terminating resistor at the beginning and end of each segment unless the
segment is less than 10 ft. (3m) long (included with ARCDIAG485).