Chapter 4 ________________________________________________________________ Operation
VAISALA _______________________________________________________________________ 61
The transmission time and size is the following:
0.18 s at 2400 bps (10-bit char.)
10.6 Kbytes/h, 253 Kbytes/d, 7.6 Mbytes/mo. at 4 msg./min.,
uncompressed.
Message interpretation:
1ST LINE
Example:
CTA2010
☺
↵
where
=
Start-of-Heading character
CT =
Ceilometers' identification string; always CT
A =
Unit number 0 ... 9, A ... Z
20 =
Software level id 00 ... 99
1
=
Message number; this message is always = 1
0
=
Spare character for future subclasses of message
☺
=
Start-of-Text Character
2ND LINE
Example:
30 01230 12340 23450 FEDCBA98
↵
Second line of CT25K data message No. 1 is identical to that of CL31
data message No. 1 (see the message interpretation in section CL31
Data Messages No. 1 on page 45), except for the status bit string,
which is 4-byte hex coded. The status bit string is coded as follows:
where
FEDC
BA98
= Alarm (A), Warning (W), and internal status information. Each character is a
hexadecimal representation of four bits, that is, values between 0 and 9 are
presented with respective numbers and values 10, 11, 12, 13, 14, and 15 are
presented with letters A, B, C, D, E, and F respectively. As each character
represents the sum of four individual bits, the total number of bits is 32 (b00-
b31), with the following breakdown and interpretation:
F:
b31
(8000 0000)
Transmitter shut-off (Laser temperature high.) (A)
b30
(4000 0000)
Transmitter failure (A)
b29
(2000 0000)
Receiver or coaxial cable failure (A)
b28
(1000 0000)
Engine, voltage or memory failure (A)
E:
b27
(0800 0000)
(spare) (A)
b26
(0400 0000)
(spare) (A)
b25
(0200 0000)
(spare) (A)
b24
(0100 0000)
(spare) (A)
