CS120A and CS125 Visibility and Present Weather Sensors
40
Table 13-1. User definable settings and descriptions
ID Name
Range
Description
Factory
default
18 Hood heater override
(1)
0-1
0 = Allow the sensor to automatically control the
hood heaters
1 = Turn the hood heaters off
0
19 Dirty window
compensation
0-1
0 = No compensation applied
1 = Compensation for dirt on lenses applied.
The sensor will compensate for up to 10% signal
loss due to dirt per lens.
0
20 Use CRC-16
0-1
0 = Disable command line CRC-16 checking
(2)
1 = Enable command line CRC-16 checking
Note: this does not affect communications via
DevConfig or terminal emulator.
0
21 Sensor power down
voltage
7-30
PSU Input voltage level below which the sensor
will enter low power mode. This is usually used to
protect batteries.
7.0
22 Relative humidity
(3)
threshold
1-99
Threshold at which the sensor will define
obscuration as liquid or dry if a CS215 is fitted.
80%
(1) Hood heater override needs to be set to ‘1’ (off) when either no hood heaters are installed or the
hood heaters have no power connected to them. This will save power as the relay is not enabled at
low temperatures in this mode.
(2) If disabled the sensor does not check the validity of received data against the checksum sent. It
is, however, recommended that checksum checking is enabled to remove any chance of the sensor
being configured incorrectly by accident.
(3) CS125 only.
14. Command line mode
The command line interface is broken down into three major commands.
These are GET, SET and POLL. The GET command is used to request all
current user settable values from the sensor. The SET commands sets user
settable values and the POLL command is used to request the current visibility
and/or alarm conditions from the sensor.
The sensor can be configured to expect any commands sent to it to include a
valid checksum. For simple commands, e.g. GET and POLL, fixed value
checksums can be used (see the downloadable example programs at
www.campbellsci.com/downloads/cs125-example-programs
www.campbellsci.com/downloads/cs120a-example-programs
). For more
complex SET commands the checksum needs to be calculated (see Appendix
Example C code of the CRC-16 checksum
(p. B-1)
). The use of the checksum
is disabled by default. It is recommended that the checksum functionality is
enabled where possible, especially when long cable runs are used, or in
electronically noisy environments.
14.1 The SET Command
The set command is used to configure the sensor via the command line. The
SET command is a single space delimited string that can be sent from any data
logger or PC equipped with serial communications. The SET command and
the ‘Device Configuration Utility’ software access identical settings within the
sensor, please refer to the ‘Device Configuration Utility’ section of this
document for a more detailed breakdown of the setting available here. This
command is used to change the default power up state of the sensor. See
