SmarTek Systems SAS-1 Detailed Communication Formats - Manual (Page 5)

SmarTek Systems (www.smarteksys.com) 5
2 to 8 7 Characters Sensor ID (i.e. SAS0001, SAS0002, etc.)
9 to 11 3 Characters Temperature (degrees F, 101, -12, +33, etc.)
12 Byte No. of Current Detections + 32
13 Byte First Detection Index + 32
14 Byte First Detection Source Level + 32
15 Byte First Detection LD Index + 32
16 Byte Second Detection Index + 32
17 Byte Second Detection Source Level + 32
18 Byte Second Detection LD Index + 32
.......................Repeat Pattern for each detection..................
12+N*3+1 Byte Health Status Code + 32
12+N*3+2 to 9+N*3+5 4 Characters Check Sum
12+N*3+6 Character Ascii Character 3 (End of Text)
All byte data have been offset by 20H (32 Decimal) to keep their values away from ASCII
control code values. Upon reception of these, subtract the offset before interpreting the data.
Depending on the SAS-1 setup, the above message will be output synchronously every Rpt_Intv
seconds (1 to 220 seconds) or when polled by a controller using the following command:
{SASxxxx,AZDET=Chr(33)}
Command to SAS-1: Start Single Zone Relay Signals Reporting
{SASxxxx,RELAY=Comm_Mode}
Comm_Mode ia a byte (1-Polled, 2-Periodic) and is offset by +32 (20 Hex).
SAS-1 Response:
Chr(2)SASxxxx<20 bytes>Chr(3)
where SASxxxx is the sensor identification number (i.e. SAS0000, SAS0001, SAS0002, etc.),
Chr (2) and Chr(3) are the start of message and end of message characters. The SAS-1 formats
the vehicle presence relays in a multi-time point, bit serial format. The 20 byte message packet
represents 10 time points with an update time of 8 milli-seconds (one message covers 80 milli-
seconds). The vehicle presence relays for five (5) zones are represented by the first 5 bits of
each byte. Each time point is a pair of bytes with the first byte representing the “upstream
relays” for each of up to 5 lanes and the second byte representing the “downstream relays” for
each of up to 5 lanes. When using the above command to start periodic or polled operation (as
opposed to using the default mode parameter, D_MODE), the 5 downstream relays (second byte)
have no meaning. Note that each byte is offset by 32 (20 Hex) to shift the byte data away from
the ASCII control codes. Hence, 32 (20 Hex) must be subtracted from each byte before
interpreting each bit state. This message relative to “dual loop speed trap” emulation is only
valid for default mode operation (D_MODE=96 to 110). The above message will be output
periodically (every 80 milli-sec) or when polled by a controller using the following command: