Chapter 7 ___________________________________________________  Retrieving Data Messages
VAISALA______________________________________________________________________ 105
Start Measurement Command with 
CRC (aMC)
Command format: aMCx!
This command asks the device to make a measurement and a three-
character CRC is added to the response data strings before <cr><lf>. 
To request the measured data, use the Send data command aD, see  Send 
Data Command (aD), on page 107.
Start Concurrent Measurement (aC)
Use this command when there are several devices on the same bus and 
simultaneous measurements are needed from the devices, or if more 
than nine (9) measurement parameters are requested from a single 
device.
The measured data is not sent automatically. You must request it with 
the Send data command aD. See Examples of aM, aC and aD 
Commands on page 108.
NOTE
When the measurement takes less than one second, part two of the 
response is not sent. This is the case in the precipitation measurement 
aM3.
NOTE
The maximum number of parameters that can be measured with aM 
and aMC commands is nine. If more parameters must be measured, 
use Start concurrent measurement commands aC and aCC (for which 
the maximum number of parameters to be measured is 20). See  Start 
Concurrent Measurement (aC), on page 105 and  Start Concurrent 
Measurement with CRC (aCC), on page 107