SmarTek Systems SAS-1 Operating Modes and Architecture - Manual (Page 4)

SmarTek Systems (www.smarteksys.com) 4
SAS-1 Hard Wire Home Run to Roadside Cabinet
The SAS-1 may be connected to equipment in a roadside cabinet that may be only several feet
from the SAS-1 or may be hundreds or thousands of feet from the SAS-1. The basic SAS-1
configuration uses a hard-wired home run cable to get power and control signals from the
cabinet to the SAS-1 and signals/messages from the SAS-1 to the cabinet controller (Figure 1).
Multiple SAS-1 units may also share a single home run cable if each SAS-1 unit is set up with a
different SAS ID and each is setup to be polled.
The SAS-1 has a small footprint and does all processing necessary for monitoring up to five
highway lanes. The SAS-1 unit is configured at the factory with the specified communication
protocol (RS-422 is standard) and provides solid state surge protection between all data lines and
ground and between the +VDC line and ground. Each SAS-1 can be set up with a selectable
SAS ID and can be set to wait for polling so that multiple SAS-1 units can share a common
communication channel without interference. That channel may be hard wired or wireless.
The SAS-Junction Box (SAS-JB) is a small, strap-on, weather-tight enclosure that is mounted
conveniently on the roadside structure. It is used to connect the short home run cable from one
or more SAS-1 units to a much longer home run cable if long runs to a roadside cabinet are
required or if a single home run cable is to be shared. The SAS-JB also provides the means to
configure the SAS-1 system with an additional stage of gas tube surge protection.
The Short Home Run Cable ships with each SAS-1 unit and is specified at the time of ordering
to be between 20 and 50 feet. The short home run cable has four pairs of stranded 24 gauge
Figure-1 SAS-1 Architecture Using Hard Wire Home Run Cable
Multiple SAS-1s
SAS Junction Box
(SAS-JB)
SAS Cabinet Termination
(SAS-CT)
Cabinet Controller or
Controller Interface
Short HR Cable (up to 50 ft.)
Long HR Cable (up to 2000 ft.)
(RS-422)
- SAS Relay Interface
- SmarTek T-BOX
- Other Controller
Roadside Cabinet
Roadside Structure
Cable Run RS-232