Lufft CHM 15k, User Manual

Page: 22 / 73

Operating Manual CHM 15k R13 / 07-2019
Commissioning and Decommissioning 22
7
Commissioning and Decommissioning
7.1 Starting up with the RS485 connection
Requirements:
•
The CHM 15k ceilometer must be installed correctly.
•
Control cable (RS485), grounding cable and mains cable (115 VAC or 230 VAC) must be
connected
•
A terminal program, e. g. HyperTerminal under Windows, is provided for monitoring
communication, which is configured for communication as follows:
- Baud rate: 9,600
- Data bits: 8
- Parity: none
- Stop bits: 1
- Flow control: none
CAUTION
After s itching on the po er supply, the CHM 15k emits Class 1M invisible laser
radiation through the opening at the top of the sensor. When viewed with optical
instruments, Class 1M radiation can lead to serious eye injuries.

Never view the laser beam with optical instruments, especially binoculars

Avoid looking directly into the laser beam
After connecting the supply voltage, the CHM 15k will start up by itself. During the start-up process an
internal self-check is done, e. g. the fans start for a few seconds. Communication with the device is
possible within 1 minute. The CHM 15k will be fully operational after a temperature adjustment phase of
varying length depending on outdoor temperature conditions. The time until measurement data are
available in high quality, can be between 2 minutes (warm start) and one hour (cold start at -40 °C).
The CHM 15k automatically send out standard data telegrams when start up procedure is ready. It is part
of the default setup and might differ for user specific CHM 15k start settings. The automatic output every
15 s is helpful to check if the communication works correctly without entering any command.
To change the start-up behavior like polling vs auto mode or the telegram that should be used at start
see chapter 8 Communication via RS485 & Ethernet.
Test commands for RS485 communication
To test the communication, use the command (RS485Number = 16 (default value):
set<SPACE><RS485Number>:Transfermode=0<CR><LF>
This changes from auto to polling mode. Testing in polling mode is helpful to avoid interruptions by
automatically sent out telegrams while typing. 9 telegram types are available:
•
Standard data telegram (short name: 1 or s)
•
Extended data telegram (short name: 2 or l)
•
Raw data telegram (short name: 3 or a)
•
User telegrams (short names: 4, 5, ..., 9)
The different telegrams can be tested, and device settings made. Section 8 describes the possible
commands and their effects in detail.
Some commands for functional testing required in routine operation or to setup the system in the
beginning are listed in Table 3
.