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1XC4+X+2.4+FD! will leave slope unchanged (default if never programmed), sets offset to 2.4 and
puts factory-default values for all the remaining parameters
Verification and Reading current Set-up
There are 2 options to read set-up
1.
aXCm (1XC4! in our examples) command which returns
a+s+o+p+t+v+i<CR><LF> or
a+NC<CR><LF> if Mm is not set to measure Counts.
2.
aXGm (1XG4) command if you are not sure whether Mm measures Counts or something else. Refer
to appendix A for description on XGm command.
Frequency Measurement
Frequency can be measured on channel DIN or AN4. Channel DIN can be configured with an internal pull-up
or pull-down, but channel AN4 has no internal pull-up or pull-down devices.
SDI-12 set-up command
To set-up for frequency measurement or change a parameter (other than default), use
aXFm+t+s+o+p+i+v+w+x!
Where,
a: SDI-address of module
m: Measurement number (M command number : 1…9)
t: Time-scale (time period over which the frequency is measured), default is 1 second.
s: Slope (default is 1.00). It is a multiplier to convert frequency to an engineering unit (m/s or f/s)
o: Offset (default is 0.00). A constant value to be added to the result after adjusting it with Slope
p: Measurement channel, „D‟ for DIN and „4‟ for AN4. (Default is D, i.e. DIN)
i: L=Enable internal pull-down, H=Enable internal pull-up, O=floating (no pull-up or pull-down). This
parameter is valid only when the channel is D, otherwise it is ignored and taken as O. (by default, it is O
for both the channels)
v: switching de-bounce time, default 0.000, i.e. 0mS. De-bounce time limits the maximum frequency that can
be measured. If de-bounce time is set to 1 mS, you can-not measure a frequency above 1 kHz.
w: Switched voltage during measurement ( = 0, 5 or 12). Default is 0
x: Switched voltage warm-up time in sec. Default is 0.1, i.e.100mS
Examples
Consider configuring M4 to measure frequency in module at SDI-12 address 1
To configure M4 to measure frequency with factory default parameters, use
1XF4+FD!
Which will configure the M4 command in the module at SDI-12 address 1 to measure the frequency
of the signal on the DIN channel with the factory defaults: slope=1.00, offset=0 with no pull-up or
pull-down, de-bounce-time=0mS.
To change just the time scale to 2.5 seconds (to measure very low frequencies), use 1XF4+2.5!
To set the slope to 2.4 and leave all other parameters unchanged (default if never programmed), use
1XF4+X+2.4!