700-SDI-PT-KEL-Man Rev 4 06 Jan 2020
8/19
3.4
MEASUREMENT COMMANDS
The Start Measurement command triggers a measurement on the addressed sensor. The sensor will
not return data, instead the sensor will return the duration of the measurement as well as the
number of data points returned by the measurement. The data is read using a subsequent Request
Data command (
aD0!
)
Measurement commands are in the following general format:
String
Comment
Cmd
aM
[n]
!
Start a measurement on sensor at the address indicated.
[n] = optional - input the number of the measurement command for
commands other than M! (ie: M1 – M4)
Resp
atttn
a
SDI address
ttt
measurement delay until data is ready in seconds
n
the number of measurement values the sensor will make
and return in one or more subsequent D commands; n is a
single digit integer with a valid range of 1 to 9
MEASUREMENT COMMANDS
The addition of the C in the command string will include the CRC (cyclic redundancy check).
Command
Response Values Measured
(send
a
DO! command to retrieve)
aM!
aMC!
a0012
After 1 second, 2 measurements available:
•
Pressure
•
Temperature
aM1!
aMC1!
a0002
After 0 seconds, 2 measurements available:
•
Minimum Pressure in bar
1
•
Maximum Pressure in bar
1
aM2!
aMC2!
a0002
After 0 seconds, 2 measurements available:
•
Minimum Temperature in
C
1
•
Maximum Temperature in
C
1
1 – the values for the M1 and M2 commands are always returned in the stated units of measurement
regardless of the selected temperature and pressure units. These values are available directly after
the command and therefore do not generate a service request.
The sensor sends a service request approximately 0.5 seconds after the ‘M’-command. After this
service request the measured data can be collected with the ‘D0’-command.
Additionally, it is possible to read out the pressure range over the ‘M1’-command as well as the
temperature range over the ‘M2’- command. These information values are available directly after
the command and therefore do not generate a service request.
