User's Manual

98 APPeNdiX
possible to increase the maximum cable length by wiring a pair of lines normally
used for RS-232 communications with the red and black wires.
If the cable length is 200 ft. (61 m) or greater you cannot reliably use RS-232
communications. To add 400 ft. (121.9 m) and achieve a maximum cable length of
1000 ft. (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 sacrice
additional communication pairs to increase the maximum cable length for
power. However, you may desire to communicate to the sensor over two
independent channels, in which case you will need to consider an alternate cable
for power. The AWG for wire pairs that achieve a 2000 ft. (609.6 m) maximum
cable length or greater at 12 and 24 V are listed in Table A.5.
To achieve reliable wired communications, the selected baud rate must be
compatible with the length of the cable run. Table A.5 below shows the cable
length recommendations for wired communications:
Baud Rate (bps) RS-232 RS-485
115200 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)
Maximum Cable Length for Wired CommunicationsTable A.5 –
To provide two independent communication channels with a homerun cable
length over 200 ft. (61 m), convert the RS-232 data into RS-485 using a Click! 304
in a pole-mount cabinet mounted next to the sensor. In this case, the homerun
connection establishes one RS-485 channel over the normal white/blue wire
pair and another RS-485 channel over the yellow/violet wire pair. An additional
Click! 304 is needed to convert the data sent over the yellow/violet wire pair back
to RS-232 before connecting to surge protection.
If you elect to use an alternate cable for power, you may also want to select an
alternate cable for RS-485 communications. Some options include the Belden
3105A (Paired – EIA Industrial RS-485 PLTC/CM) or Alpha Wire 6010C 3PR 22
AWG.
There are many reliable options available for wired power and communications
connections (see Table A.6).