SmarTek Systems SAS-1 Detailed Communication Formats User Manual
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SmarTek Systems (www.smarteksys.com)
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Chr(2)SASxxxx
LL
LL
LL
LL
where PPP is the message position in the SAS-1 FIFO buffer, LL is the lane number, VVV is
the total vehicle volume or count, UUU is the commercial truck count, WWW is the tractor-
trailer count, OOO is lane occupancy in percent, SSSS is average speed in mph. Spaces (ASCII
Chr (32)) in the format are designated as
and line feed respectively. Chr (2) and Chr(3) are the start of message and end of message
characters. Note that this entire message is ASCII. When polling the SAS-1, PPP indicates
whether the message is current (PPP=1), or old and should be dropped (PPP=0), or behind
(PPP>1). If the “Poller” is behind, the SAS-1 should be immediately repolled (and the message
kept) until PPP=1.
Depending on the SAS-1 setup, the above message will be output periodically every Rpt_Intv
seconds (1 to 220 seconds), or when polled by a controller using the following command:
(Simple flow message)
or
(Message with truck counts).
If either of the above polling commands is sent with a SAS ID of SAS0000, each connected
SAS-1 will respond with a 0.25 second delay according to its SAS ID. For example, if the
broadcast flow command of
is sent out to connected SAS-1 units, SAS0001 will respond after 0.25 seconds, SAS0002 will
respond after 0.5 seconds, SAS0003 will respond after 0.75 seconds and so on. This facilitates
the ordering of SAS-1 messages from a remote site without the need of a local controller and
eliminates the need to poll individual SAS-1 units.
Command to SAS-1: Start Azimuth Detection Reporting (SAS Monitor Mode=3)
Comm_Mode is a byte (1-Polled, 2-Periodic) and is offset by +32 (20 Hex).
SAS-1 Response:
Byte #
Data Type
Description
1
Character
Ascii Character 2 (Start of Text)