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acquire bridge measurements

this example shows how to acquire and plot data from an ni usb-9219 device. the device id is cdaq1mod7.

create a dataacquisition object assigned to the variable d:

d = daq("ni");

add an analog input channel for bridge measurement type, assigned to the variable ch:

ch = addinput(d,"cdaq1mod7","ai1","bridge");

you might see this warning:

warning: the rate property was reduced to 2 due to the default adctimingmode of this device,
which is 'highresolution'.
to increase rate, change adctimingmode on this channel to 'highspeed'.

to allow a higher acquisition rate, change the channel adctimingmode to 'highspeed':

ch.adctimingmode = "highspeed"

you might see this warning:

warning: this property must be the same for all channels on this device.  all channels
associated with this device were updated.

change the acquisition rate to 10 scans per second.

d.rate = 10;

set the channel bridgemode to 'full', which uses all four resistors in the device to acquire the voltage values:

ch.bridgemode = "full"
ch = 
data acquisition analog input channel 'ai1' on device 'cdaq1mod7':
             bridgemode: full
       excitationsource: internal
      excitationvoltage: 2.5
nominalbridgeresistance: 'unknown'
                  range: -0.063 to  0.063 voltspervolt
                   name: empty
                     id: 'ai1'
                 device: [1x1 daq.ni.compactdaqmodule]
        measurementtype: 'bridge'
          adctimingmode: highspeed

set the resistance of the bridge device to 350 ohms:

ch.nominalbridgeresistance = 350
ch = 
data acquisition analog input channel 'ai1' on device 'cdaq1mod7':
             bridgemode: full
       excitationsource: internal
      excitationvoltage: 2.5
nominalbridgeresistance: 350
                  range: -0.063 to  0.063 voltspervolt
                   name: empty
                     id: 'ai1'
                 device: [1x1 daq.ni.compactdaqmodule]
        measurementtype: 'bridge'
          adctimingmode: highspeed

save the acquired data to a variable and start the acquisition:

data = read(d,seconds(1),"outputformat","matrix")

plot the acquired data:

plot(data)

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