SmartSensor HD - Interprovincial Traffic Services

94 APPENDIX • SMARTSENSOR HD USER GUIDECable Gauge 24 Volts 12 Volts20 AWG (SS Cable) 600 ft. (182.9 m) 110 ft. (33.5 m)Additional 22 AWG Add 400 ft. (121.9 m) Add 75 ft. (22.9 m)22 AWG (Old SS Cable) 400 ft. (121.9 m) 75 ft. (22.9 m)Additional 22 AWG Add 400 ft. (121.9 m) Add 75 ft. (22.9 m)14 AWG 2500 ft. (762 m) 450 ft. (137.2 m)12 AWG 3900 ft. (1188.7 m) 700 ft. (213.4 m)10 AWG 6000 ft. (1828.8 m) 1050 ft. (320 m)8 AWG 9900 ft. (3017.5 m) 1750 ft. (533.4 m)6 AWG 14,000 ft. (4267.2 m) 2500 ft. (762 m)Table C.1 – Maximum Cable Length for PowerIf the cable length is longer than 600 ft. (182.9 m) when operating at 24 VDC, it is possibleto increase the maximum cable length by wiring a pair of lines normally used for RS-232communications with the red and black wires.In many cases, if the cable length is 200 ft. (61 m) or greater you cannot reliably use RS-232communications. To add 400 ft. (121.9 m) and achieve a maximum cable length of 1000ft. (304.8 m), connect the orange wire (normally RTS) to the red wire and the brown wire(normally CTS) to the black wire.If your cable run is longer than 1000 ft. (304.8 m), it is possible to sacrifice additionalcommunication pairs to increase the maximum cable length for power. However, you maydesire to communicate to the sensor over two independent channels, in which case you willneed to consider an alternate cable for power. The AWG for wire pairs that achieve a 2000ft. (609.6 m) maximum cable length or greater at 12 and 24 VDC are listed in Table A.1.To achieve reliable wired communications, the selected baud rate must be compatible withthe length of the cable run. Table C.2 below shows the cable length recommendations forwired communications:Baud Rate (bps) RS-232 RS-485115200 40 ft. (12.2 m) 300 ft. (91.4 m)57600 60 ft. (18.3 m) 600 ft. (182.9 m)38400 100 ft. (30.5 m) 800 ft. (243.8)19200 140 ft. (42.7 m) 1000 ft. (304.8 m)9600 200 ft. (61 m) 2000 ft. (609.6 m)Table C.2 – Maximum Cable Length for Wired CommunicationsTo provide two independent communication channels with a homerun cable length over200 ft. (61 m), convert the RS-232 data into RS-485 using a Click 304 in a pole-mountcabinet mounted next to the sensor. In this case, the homerun connection establishes one