FTS DigiTemp - Page 11

DigiTemp User Manual Chapter 2 SDI Commands
page 11
2.4.1 Start Measurement
This command is used trigger 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 Send Data command. Refer to Tables 2 and 3 for the
specifics of the data returned from the sensor.
String
Note
Cmd
3M! or 3MC!
start a measurement on sensor at address 3 (without or
with CRC in data response, respectively)
Resp
30032
3 device SDI address
003 measurement delay (until data is ready; seconds)
2 number of data points returned
2.4.2 Start Concurrent Measurement
The concurrent measurement command allows a sensor to take a measurement while other SDI sensors are
also taking measurements. The Start Concurrent Measurement Command operates in the same manner and
returns the same information as the Start Measurement command (refer to Table 2).
String
Note
Cmd
3C! or 3CC!
start a concurrent measurement on sensor at address 3
(without or with CRC in data response, respectively)
Resp
300302
3 device SDI address
003 measurement delay (until data is ready; seconds)
02 number of data points returned
2.4.3 Send Data
This command requests the data generated by the preceding Measurement (M or C) command. An aD0!
command is always the first command sent to retrieve the data. If additional data needs to be read, then an
aD1! command is sent, then and aD2! etc. etc., up to aD9!. Since the DigiTemp returns only two values
(temperature in degrees C and F), only an aD0! command is ever required with it.
String
Note
Cmd
3M!
start a measurement on sensor at address 3
Resp
30032
3 device SDI address
003 measurement delay (until data is ready; seconds)
2 number of data points returned
Cmd
3D0!
request data from previous measurement command
Resp
3+11.4+52.5
3 sensor SDI address
+11.4 temperature in degrees Celsius
+52.5 temperature in degrees Fahrenheit
Cmd
3MC!
start a measurement on sensor at address 3, with CRC in
data response
Resp
30032
3 device SDI address
003 measurement delay (until data is ready; seconds)
2 number of data points returned