Start measurement command (aM) - WXT530

WXT530 Series User Guide

Document code
M211840EN
Revision
F
Language
English (United States)
Product
WXT530
Document type
User guide

This command asks the device to make a measurement. The measured data is not sent automatically. You must request it with the Send data command aD.

The host device is not allowed to send any commands to other devices on the bus until the measurement is completed.

When several devices are connected to the same bus and simultaneous measurements from the many devices are needed, use start concurrent measurement aC or start concurrent measurement with CRC aCC.

Command format:

aMx!
a Device address
M Start measurement command
x The desired sensor to make the measurement
1 = Wind
2 = Temperature, humidity, pressure
3 = Precipitation
4 = Analog input
5 = Supervisor
If x is left out, the query refers to the combined data message used for requesting data from several sensors with one command.
! Command terminator
For analog input measurements, the measurement completing time is the bigger one of the aUI,A and aIP,A values (averaging times for solar radiation, ultrasonic level sensor and Aux.temperature).

The response is sent in two parts.

Part one:

atttn<cr><lf>

Part two (indicates that the data is ready to be requested):

a<cr><lf>
a Device address
ttt The measurement completing time in seconds
n The number of the measured parameters available (maximum number is 9)
<cr><lf> Response terminator
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.
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).