Vaisala WMT700 - Manual (Page 73)

Chapter 5 ______________________________ Operating WMT700 with WS425 and SDI-12 profiles
VAISALA _______________________________________________________________________ 71
WS425 A/B SDI-12 Message for V Command
When you have given the commands aV! and aD0!, the response is the
following:
a<watchdog><WS_unit><SDI-mode><spare><CR><LF>
where
a
= The single-digit WMT700 address that corresponds
to the first character of the address value.
<watchdog> = The number of times the watchdog has triggered.
Ideally should be zero. Format: +(c)c
<WS_unit> Wind speed unit. The options are:
+0 = mph
+1 = kt
+2 = km/h
+3 = m/s
<SDI-mode> Current sub mode setting. The options are:
+0 = SDI-12 sub mode A
+1 = SDI-12 sub mode B
<spare> 1 digit for factory use, format: +c
<CR><LF> Terminates the response.
The above are verification data fields.
Requesting Cyclic Redundancy Check
Error detection capability can be enhanced by using aCC! or aMC!
command to start the measurement. These commands have the same
function and send the same response as commands aC! and aM!
respectively. The difference is, that Cyclic Redundancy Check will be
appended to the data returned by aD0! command.
The 16 bit Cyclic Redundancy Check value is appended to the response
of aD0! command before the <CR><LF>. It is encoded as three ASCII
characters using the following algorithm:
1st character=0x40 OR (CRC shifted right 12 bits)
2nd character=0x40 OR ((CRC shifted right 6 bits) AND 0x3F)
3rd character=0x40 OR (CRC AND 0x3F)