43
8
Z-Axis High Byte
9
Z-Axis Low Byte
10
End Character – always $
The length of the data frame can vary depending on the number of active channels. For example,
if the X-channel is inactive, all the data will be shifted-up in the frame by two bytes.
The threshold setting is also different in the binary mode in that a report will still be generated
even if it’s below the threshold setting, but it will read ‘1025.’ This is to ensure that the data
frame is always a known length.
The ‘Sample Number’ increases with every output and will roll-over at 65535. The X, Y, and Z
Axis are in 16-bit binary form. They are numbers directly returned from the ADC of the
accelerometer.
Threshold
A threshold setting has been added in the g-Analyst. For example, by setting the threshold to
0.5g, only accelerations greater than 0.5g will be displayed. By returning the threshold to 0.0g,
all acceleration values will be reported.
From the top menu, press ‘6’ to get into the threshold setting mode. You will then be prompted
to press ‘i' to increase or ‘d’ to decrease the threshold setting in 0.1g increments.
Note: make sure you are working with a good calibration before setting this to a non- zero value.
Output Frequency
From the top menu, press ‘7’ to enter the output frequency select mode. You will then be
prompted to press ‘i' to increase or ‘d’ to decrease the output frequency in 5 Hz steps.
Each display mode has a maximum output frequency setting:
•
Gravity Mode = 135 Hz
•
Raw ADC Mode = 220 Hz
•
Binary Mode = 610 Hz
It is possible to select an incorrect setting if you don’t set the output frequency after changing the
display mode.
Note: the g-Analyst is designed to measure vehicle motion. Therefore, the bandwidth of the
acceleration signal has been set to 25 Hz to minimize noise.
