Campbell Scientific CS135 Lidar Ceilometer - Manual (Page 16)

CS135 Ceilometer
8
Signal voltage levels
Minimum
Value
Nominal
Value
Maximum
Value
RS232 Communications
RS232 input threshold Low 0.8V 1.5V -
RS232 input threshold High - 2.0V 2.4V
RS232 input absolute maximum -15V - +15V
RS232 input resistance 12K
Ω
- -
RS232 output voltage low - - 0.4V
RS232 output voltage high (into
3K
Ω)
4.4V - -
RS485/422 Communications
RS485/422 input threshold
voltage -0.2V - +0.2V
RS485/422 output (Unloaded) - - 5V
RS485/422 output (Load 50
Ω)
2V - -
Maximum voltage at any terminal -7V - +7V
USB Service Port USB1.1 and 2.0 compatible, fixed 115200 baud.
3. Initial checks
The following steps will provide basic familiarisation with the CS135 and
perform basic functionality checks. To do these you must first remove the cover
and enclosure lid (see Sections 4.6.1 and 4.6.2) and then connect the battery (see
Section 4.6). Connect the hood heater plug once you have done these stages. See
Fig 4.3 in Section 4.5.1.
The laser will be operating as soon as the battery is
connected. It should not point in any direction where it
could be viewed with magnifying optics.
The green LED visible from above should now be flashing once every 10 seconds
(see Fig 5.2).
Connect a PC using a terminal emulation program to the USB port (Fig 4.5). The
terminal emulator should be set to 115200 baud, 8N1 bits/parity.
PC operating systems should identify the USB connection and allocate a port
number. The terminal emulator program you are using should then be set to this
port number. Older PC operating systems may need upgrading or additional
software.
The CS135 will be outputting message type 001 every 10 seconds (see Section
6.2).
Open terminal mode with the command “open 0”. You should now see the prompt
“CS135>”, Type “Status”. You will now see the sensor status information
described in Section 5.1.5. If you plan to use date/time information this should be
checked as it can drift up to ±14 seconds per day.
WARNING