Campbell Scientific TDRSDK Software Developement Kit - Manual (Page 21)

A-1
Appendix A. TDR100 Command
Protocol
:XXXX ffffffffHLcr Type 1 commands to set a variable (space between
command and value)
:XXXXHLcr Type 2 & 3 commands
: Start of Command
XXXX Command ASCII Characters
ffffffff Floating point number in ASCII characters preceded by a
space. No maximum number of characters, a single
floating point value.
HL Hexadecimal representation of 8 bit Checksum which
includes all characters after ‘:’ and before the checksum.
Computed by summing each character and discarding any
carries.
H = high order bits, L = low order bits.
cr Carriage Return
:XXXX One of the following 4 character commands.
Type 1 Commands (Set a variable)
:S_VP n Set Vp value
:SDIS n Set Distance (Cable Length)
:SMAX n Set maximum display value
:SMIN n Set minimum display value
:SMUX n Set SDMX50 channel
:SNAV n Set Number of Averages
:SPCC n Set Probe Cell Constant
:SPNT n Set Number of Points
:SPRL n Set Probe Length
:SPRO n Set Probe Offset
:SSMO n Set Smooth Value
:SWLN n Set Window Length
:CCCC n Calculate Cell Constant (special type-1 cmd that returns
value like type-2 cmd)