Measurement Computing DAQFlex for Android Quick Start - Manual (Page 5)

Sending a Message
5
During the normal Android activity lifecycle, the activity may be destroyed any time after the onPause()
callback. If you created the DaqDevice object inside of the activity, the DaqDevice object is also destroyed.
Make sure to call the close() method during the activity onPause() method.
Managing the activity lifecycle is particularly important when running scan operations. Because the
DaqDevice object may get destroyed by the activity, stop any active scan operations before calling the
DaqDevice close() method.
If a scan must continue while the application is paused, start an Android Service to hold the DaqDevice object
and to keep it open in the background. Failure to do so will result in a buffer overrun and data loss.
Sending a Message
After the device has permission and is opened, you can start sending messages to the device. Call the
DAQDevice sendMessage() method. The sendMessage() method accepts a string command to send to the
device.
For documentation on the DAQFlex command format, refer to the DAQFlex Software Help for the desktop API
at
www.mccdaq.com/pdfs/manuals/DAQFlex Software.pdf and the Supported Messages section in this
document.
Reading Analog Input Scan Data
Tablet CPU limitations affect the sampling rate
Analog input scans do not run at full speed for all devices due to tablet CPU limitations. Using minimal display
code on a low-end tablet, a maximum of 150 kS/s aggregate was achieved using this API with USB-1608G
Series devices.
After sending an AISCAN:START message, scan data is read with the readScanData() method. Data is
returned as a double[][] data type, with the channel number as the first dimension and the sample number as
the second. This method is overloaded so that if no arguments are passed to the method, the method returns all
available data. Passing the number of samples and timeout only returns that number of samples.
Supported Messages
DAQFlex for Android supports the following messages. Refer to the DAQFlex Software Help for the desktop
API at
www.mccdaq.com/pdfs/manuals/DAQFlex Software.pdf for more detailed information on these
messages.
If a message from subsequent DAQFlex releases is not in the following table, or if a supported message returns
an unknown status, that message may or may not function correctly.
Component Properties
DEV
FLASHLED, FPGACFG, FPGAV, FWV, ID, MFGCAL, MFGSER, RESET, STATUS/ISO,
TEMP
AI
CAL, CHMODE, CJC, DATARATE, OFFSET, RANGE, RES, SCALE, SENSOR, SLOPE,
STATUS, VALUE
*
AISCAN
*
BURSTMODE, CAL, COUNT, HIGHCHAN, LOWCHAN, RANGE, RATE, RESET,
SAMPLES, SCALE, START, STATUS, STOP, XFRMODE
AO OFFSET, RANGE, REG, RES, SCALE, SLOPE, UPDATE, VALUE
CTR START, STOP, VALUE
DIO DIR, LATCH, VALUE
TMR DELAY, DUTYCYCLE, IDLESTATE, PERIOD, PULSECOUNT, START, STOP
*Temperature channels are not currently supported during an AISCAN . Temperature channels can be read with
the single-point AI:VALUE message.