45
The following measurement set descriptions detail the parameters returned by each of the measurement commands.
For the aM! command, only the default reading set is listed.
All data transmitted using SDI-12 must be printable ASCII characters. The first character of any command or
response is the address. The lowercase 'a' at the beginning of each command represents the address character.
SDI-12 Measurement Sets
Response Parameters – Refer to Table 1
Command
P1 P2 P3 P4 P5 P6 P7 P8 P9
aM!
H
J
F
G
O
K
M
L
N
aM1!
F
G I
aM2!
F
G
H
O
I
aM3! K
L
M
N
O
P
Q
aM4!
A
B
C
D
E
aM5! R
S
T
U
V
Table 2 – Measurement Command Sets
SDI-12 Extended Command Summary
The HP2 implements a number of SDI-12 extended commands. The following table lists all of the supported
extended commands and a brief description:
SDI-12 Extended Commands
Command Description
aXS!
Get soil type
aXS<soil>!
Set soil type
aXP0!
Turn on the probe circuitry
aXP1!
Turn off the probe circuitry
aXM!
Get the default measure set
aXM=0!
Set the default measure set to set 0
aXM=1!
Set the default measure set to set 1
aXM=2!
Set the default measure set to set 2
aXM=3!
Set the default measure set to set 3
aXM=4!
Set the default measure set to set 4
aXM=5!
Set the default measure set to set 5
aXM=<set>!
Set custom default measure set
aXR!
Reset probe to defaults
aXY<constant>!
Get water constant
aXY<constant><float>!
Set water constant
aXW!
Get probe warmup time
aXW<warmup>!
Set probe warmup time
Table 3 – SDI-12 Extended Commands
<soil>
Single ASCII character representing the soil type. The default soil type is
4
.
Values:
1 Sand
2 Silt
3
Clay
4
Loam
C Custom
1
D Custom
2
<set>
String of 1-9 ASCII characters that specify the measurements taken by the standard measurement
command (aM!). Valid values are any of the letters A-V. The default measurement set is
HJFGOKMLN
.
