CS120A and CS125 Visibility and Present Weather Sensors
19
It may be necessary to use a 120 ohm termination resistor to reduce signal
distortion when using RS-485 for cable runs over about 500 m and baud rates
above 38400. It should be connected between pins 2 and 3.
Connector C -
Four way connector
Pin number
Description
Notes
Pin 1
0V
0V connection for user alarms. This connection is common with
the main electronics 0V (Connector A, Pin 2).
Pin 2
User 2
Output for user alarm 2
Pin 3
0V
0V connection for user alarms. This connection is common with
the main electronics 0V (Connector A, Pin 2).
Pin 4
User 1
Output for user alarm 1
CS125 only
Pin number
Description
Pin 1
+12V
Pin 2
SDI-12
Pin 3
0V
To use these connections it is necessary to either use the cable
gland taking the hood heater power or, if the hood heater is also
required, to use different cables to those supplied. Please contact
Campbell Scientific if you need any advice on choice of cable.
8.1 Sensor recommended wiring using Campbell Scientific
cables
(this cable is supplied already connected as standard)
The sensor is provided pre-wired with a default 5 m power and
communications cable which is terminated at one end with a 9 pin D-connector
(DB9). The D-connector can be connected directly to a PC or to a datalogger
such as the Campbell Scientific CR1000 using a suitable interconnecting cable
such as the SC110. If another type of connection is required then the D-
connector should be removed.
NOTE