Campbell Scientific CS125 Present Weather Sensor - Manual (Page 12)

CS125 Present Weather Sensor
4
RS232 output voltage high (into
3K

)
4.4V - -
RS485 Communications
RS485 input threshold voltage -0.2V - +0.2V
RS485 output (Unloaded) - - 5V
RS485 output (Load 50

) 2V - -
Maximum voltage at any terminal
(6)
-7V - +7V
User alarm outputs
User output high level (at 85ºC) 3.8V - -
User output high level (at 25ºC ) 4.13V - -
User output low (All temperatures) 0.25V - 0.55V
User output current - - 32mA
(1) If a CS215 is being used the supply voltage should not exceed 16V.
(2) The RS232 communications interface will automatically turn itself off when not transmitting.
(3) If hood heaters are not being used ensure `Hood heater override’ (details in Section 13) is set to
off.
(4) It is recommended that the hood heaters are run at 24V AC/DC. It’s possible to run the heaters at
any voltage below 24V but the heaters will generate proportionally less heat reducing their ability to
prevent ice build-up.
(5) Each hood takes 30W, 60W is the total for both hoods on the sensor together.
(6) The ground of the CS125 and the earth of any RS485 equipment cannot be further apart than this
voltage. A 100

resistor can be used to connect the CS125 RS485 earth to other equipment. This will
reduce any parasitic currents and bring the two earths closer together if a direct connection cannot be
made.
If a CS215 is being used the supply voltage should not
exceed 16V.
4. Supported data rates for RS232 and RS485
Serial setting 8N1
Supported data rates

1200 bps

2400 bps

9600 bps

19200 bps

38400 bps - default

57600 bps

115200 bps
CAUTION