Gulf Coast Data Concepts X16-4 User manual

X16-4
USB Accelerometer
Data Logger
User Manual
Document Revision: Rev B
Firmware ersion: 1110
Date: August 16, 2017

Table of Contents
1 Introduction..........................................................................................................................................1
1.1 About This Manual..................................................................................................................1
1.2 Document Conventions............................................................................................................1
1.3 Appendix..................................................................................................................................1
1.4 Product ummary.....................................................................................................................2
1.5 Feature List..............................................................................................................................2
1.6 Items Included with X16-4......................................................................................................3
1.6.1 ingle Unit Purchase..........................................................................................................3
1.6.2 5 Unit Kit...........................................................................................................................3
1.7 Component Names...................................................................................................................4
1.8 Quick tart Guide....................................................................................................................5
2 Operation..............................................................................................................................................7
2.1 U B Interface...........................................................................................................................7
2.2 Memory Card...........................................................................................................................7
2.3 Battery......................................................................................................................................8
2.4 etting The RTC.......................................................................................................................9
2.5 tatus Indicators.....................................................................................................................10
2.6 ystem Configuration Options...............................................................................................11
2.6.1 deadband..........................................................................................................................12
2.6.2 deadbandtimeout..............................................................................................................12
2.6.3 dwell.................................................................................................................................12
2.6.4 microres............................................................................................................................13
2.6.5 rebootondisconnect..........................................................................................................13
2.6.6 samplesperfile..................................................................................................................13
2.6.7 samplerate........................................................................................................................14
2.6.8 starttime and stoptime......................................................................................................14
2.6.9 stoponvusb.......................................................................................................................14
2.6.10 statusindicators.................................................................................................................14
2.7 Example Configuration Files.................................................................................................14
2.7.1 Example A........................................................................................................................14
2.7.2 Example B........................................................................................................................15
2.7.3 Example C........................................................................................................................15
3 Data Interpretation.............................................................................................................................16
3.1 Data Files...............................................................................................................................16
3.2 Data Format...........................................................................................................................16
3.3 Data Conversion.....................................................................................................................17
3.3.1 Time tamps....................................................................................................................17
3.3.2 Acceleration.....................................................................................................................18
4 ystem Details...................................................................................................................................18
4.1 ensor.....................................................................................................................................18
4.1.1 ensor pecial Features...................................................................................................19
4.2 Operating and torage Conditions ........................................................................................20
4.3 Dimensions............................................................................................................................20
5 Troubleshooting.................................................................................................................................21
A

6 Appendix............................................................................................................................................23
6.1 What is an Accelerometer......................................................................................................23
6.2 Using “R” to Analyze Data....................................................................................................25
6.2.1 What is “R”......................................................................................................................25
6.2.2 Introduction to R Commands...........................................................................................26
6.2.3 Online Resources for R....................................................................................................27
6.2.4 Example cripts in R.......................................................................................................28
Index of Figures
Figure 1: X16-4 Data Logger.....................................................................................................................2
Figure 2: X16-4 and Accessories...............................................................................................................3
Figure 3: 5 Unit kit of Loggers..................................................................................................................3
Figure 4: X16-4 Data Logger Components...............................................................................................4
Figure 5: Exploded View of the X16-4.....................................................................................................4
Figure 6: Connecting to PC........................................................................................................................5
Figure 7: Editing the Config.txt File..........................................................................................................5
Figure 8: tarting the X16-4......................................................................................................................6
Figure 9: ensor Orientation......................................................................................................................7
Figure 10: Battery Pack Connectors..........................................................................................................8
Figure 11: Expected Battery Life...............................................................................................................9
Figure 12: Example Time Entry in time.txt File.....................................................................................10
Figure 13: LED tatus Indicators............................................................................................................11
Figure 14: Graphical Illustration of the Deadband Feature....................................................................12
Figure 15: Graphical Illustration of the Dwell Feature...........................................................................13
Figure 16: Configuration File Example A..............................................................................................15
Figure 17: Configuration File Example B..............................................................................................15
Figure 18: Configuration File Example C..............................................................................................15
Figure 19: Example Data File.................................................................................................................16
Figure 20: Time tamp Conversion Method...........................................................................................17
Figure 21: 800Hz ample Configuration................................................................................................20
Figure 22: Enclosure Dimensions...........................................................................................................20
Figure 23: pring-mass Accelerometer...................................................................................................23
Figure 24: implified MEM Accelerometer Design (L) and Actual MEM Accelerometer (R).........24
Figure 25: R Command Line Interface ..................................................................................................25
Figure 26: R tudio Interface ..................................................................................................................26
Index of Tables
Table 1: Configuration File Tags and Descriptions..................................................................................11
Table 2: Data File Header Tags................................................................................................................17
Table 3: Example Data Conversion.........................................................................................................18
Table 4: Accelerometer ensor Characteristics........................................................................................19
Table 5: Operating and torage Conditions.............................................................................................20
B

1 Introduction
1.1 About This Manual
Thank you for purchasing the X16-4 accelerometer data logger. Gulf Coast Data Concepts spent
considerable efforts developing an easy to use data logger for the scientific researcher, student, or
hobbyist. Please read this manual to understand the operation and capabilities of the X16-4. If the
logger fails to operate as expected, please refer to the troubleshooting guide (page 21).
1.2 Document Conventions
The quick start guide in section 1.8 provides a basic summary of operation to begin using the X16-4
data logger. This user manual continues into further details of configurations and capabilities starting
in section 2. Each section also presents relevant tips and warnings to help the user.
This icon indicates a helpful tip that may enhance the performance of the logger or aide in
the application of the logger.
This icon indicates a warning, restriction, or limitation that the user should be aware of
regarding the logger operation.
1.3 Appendix
The appendices to this document include several educational discussions regarding accelerometers
(section 6.1) as well as software and analysis procedures (section 6.2). These short discussions will
help new users learn about the X16-4 and how to use the data.
Gulf Coast Data Concepts Page 1 X16-4, Rev B

1.4 Product Summary
The X16-4 is a low cost and compact self-recording accelerometer data logger. Data from the digital 3-
axis accelerometer sensor is time stamped using a real time clock and stored to a micro D card in
simple text format. When connected via the U B to a personal computer, the X16-4 appears as a
standard mass storage device containing the comma delimited data files and the user setup file. The
X16-4 includes an internal 500mAh lithium-polymer rechargeable battery, which will recharge using
U B power.
1.5 Feature List
•3-axis ±16g accelerometer
•16-bit resolution
•User selectable sample rate of 12, 25, 50, 100, 200, 400 Hertz
•Finite Impulse Response filter
•Accurate time stamped data using Real Time Clock (RTC)
•Convenient on/off button
•Data recorded to a removable micro D card (8GB included)
•Easily readable comma separated text data files
•Data transfer compatible with Windows or Linux via Universal erial Bus (U B) interface (no
special software required)
•Operates from internal lithium-polymer rechargeable battery
•Weight 1.3oz (48g)
•ize 1x1x4.1 inch (26x26x104 mm)
Gulf Coast Data Concepts Page 2 X16-4, Rev B
Figure 1: X16-4 Data Logger

1.6 Items Included with X16-4
1.6.1 Single Unit Purchase
The X16-4 is packaged with the logger, a USB extender cable, and a screwdriver.
1.6.2 5 Unit Kit
kit includes 5 X16-4 loggers, a USB extender cable, and a screwdriver.
Gulf Coast Data Concepts Page 3 X16-4, Rev B
Figure 2: X16-4 and Accessories
Figure 3: 5 Unit kit of Loggers

1.7 Component Names
A Type-A U B connector I Enclosure top
B Blue LED status indicator J Enclosure bottom
C Red LED data indicator K Enclosure cap
D Red LED charge indicator L Enclosure hinge
E 500mAh Battery Pack M #6-32 3/4” screw
F Battery Connectors N #6 nut
G On/Off button O ADXL345 sensor
H Micro D card (under wrap)
Gulf Coast Data Concepts Page 4 X16-4, Rev B
Figure 4: X16-4 Data Logger Components
A
I
B
C
E
H
K
G
J
M
N
L
Figure 5: Exploded iew of the X16-4
0.75" Length
#6-32 Machine Screw
PCB Enclos re
(Top)
PCB Enclos re
(Cap)
PCB Enclos re
(Bottom)
On/Off B tton
#6-32 Hex N t
O
F
D

1.8 Quick Start Guide
The X16-4 is a simple, economical solution to capture continuous motion data and quickly deliver the
information for analysis. The following instructions outline the steps to begin using the X16-4.
Configuration settings and mounting methods will depend on the particular application.
tep 1: Plug the X16-4 into a computer and allow the computer operating system to register the
device as a Mass torage Device. Notice that the logger will mount with a drive label
using the last digits of the serial number. A red LED located on the bottom side will
indicate the battery is charging. The LED will turn off when the battery is fully charged,
which takes about 2 hours.
tep 2: Configure the X16-4 by editing the appropriate tags in the config.txt file using a simple
text editor. In Windows, do not use Notepad as the editor does not terminate new lines
properly. GCDC recommends Windows Wordpad or Notepad++ to edit the config.txt
file. Refer to section 2.6 for a complete list of configuration options.
Gulf Coast Data Concepts Page 5 X16-4, Rev B
Figure 6: Connecting to PC
Figure 7: Editing the Config.txt File

tep 3: If necessary, initialize the RTC clock by creating a time.txt file (see section 2.4). Once
the time.txt file is saved, immediately unplug the logger to start the initialization
process. The logger will load the time.txt file, initialize the clock, and delete the time.txt
file. Initializing the RTC ensures the data files include the correct year, month, and day
and that the data samples can be correlated to a specific date and time.
tep 4: After removing from the U B port, attach the X16-4 logger to the target object. The
logger is small and light weight so double-sided tape, Velcro, or a spot of cyanoacrylate
glue are sufficient methods of attachment.
tep 5: Press the on/off button located at the rear of the enclosure to initiate data recording, (see
Figure 8). Logging will start about 3-5 seconds after pressing the button. The red LED
will blink as the configuration file is accessed. If the time.txt file is present, the RTC is
initialized with the time written in the file. Then, the blue LED will begin to blink at a 1
second interval indicating the system is operating. The red LED will blink periodically
as data is written to the micro D card.
tep 6: To stop recording, press and hold the button for about 3 seconds. The red and blue
LEDs will begin to blink rapidly for 2 seconds and then turn off. Release the button and
the X16-4 turns off. Pressing the button again restarts the logger and data is recorded to
a new file.
tep 7: Plug the logger into a PC and allow the logger to mount as a U B drive. The data files
will appear in the “GCDC” directory.
tep 8: The data recorded to the files must be converted to determine acceleration in “g” units.
Divide the Ax, Ay, Az columns by 2048 to determine g units. ee section 3.3 for a
complete discussion of data conversion.
Gulf Coast Data Concepts Page 6 X16-4, Rev B
Figure 8: Starting the X16-4
The X16-4 is small and light weight so attachment methods do not need to be substantial.
Double-sided tape, a spot of cyanoacrylate glue (contact cement , zip-ties, magnetic base,
or adhesive putty are example methods of attachment. These methods do not cause
adverse signal attenuation considering the relatively low frequency bandwidth of the X16-4
logger. Command Poster Adhesive strips by 3M offer excellent temporary attachment of
the logger to most surfaces.

2 Operation
2.1 USB Interface
The X16-4 connects to a PC using a standard Type-A U B connector and supports the U B mass
storage device interface for file access and file transfers. Nearly all computer operating systems
recognize the X16-4 as a typical U B external memory drive. Therefore, the X16-4 will allow file
transfers to the micro D card like a common U B flash drive. When connected to a PC, the X16-4
deactivates logging and operates only as a U B interface to the micro D card. Note that some tablet
operating systems block access to U B mass storage devices and will not recognize the X16-4.
2.2 Memory Card
The X16-4 stores data to a removable micro D flash memory card located beneath the white plastic
wrap. The included 8GB card is sufficient for most applications so the card does not need to be
removed or upgraded. However, the plastic wrap can be cut away to allow access to the card. The
logger uses FAT32 and is compatible with micro D and mico DHC type cards.
The logger needs only the config.txt file to operate. The X16-4 will use default configuration settings
if the config.txt is not present. The “config.txt” and “time.txt” files must occur in the root directory
(see section 2.6 and section 2.4). The X16-4 will create a folder called “GCDC”, if not already present,
to place the data files.
Gulf Coast Data Concepts Page 7 X16-4, Rev B
Interrupting the power to the logger can result in corruption of the microSD card. For
example, removing the logger from the USB port during file transfers to the PC or
removing the battery during logging activity. Reformat the card if it becomes corrupted
(FAT32 file structure . If data transfers to/from the card become slow, consider formatting
the card using “SD Card Formatter” software provided by the SD Association
(www.sdcard.org .
Figure 9: Sensor Orientation
The white plastic wrap is used to aid the assembly process at GCDC but it can be
removed to allow access to the microSD card. The logger is USB 2.0 compliant but is
limited to about 700 KB/sec. Removing the microSD card and using a standard USB card
reader will permit faster transfer of data files.
+X
+Z
+Y

2.3 Battery
The X16-4 is powered by a internal 500mAh lithium-polymer rechargeable battery pack. The internal
battery management system recharges the battery when the X16-4 is plugged into a U B port or
attached to a U B 5v power adapter. The red charge indicator LED turns on (see ection 2.5) when the
battery is charging and off when the battery reaches full charge. The battery is not used when the
system is connected to a computer U B port. eparate connectors are used for the two individual
250mAh batteries, as noted in Figure 10. Disconnecting both connectors will deactivate the logger and
reset the system (data on the micro D card is not be affected).
The battery provides approximately 16 hours of operation sampling at 400 Hz with the deadband set to
zero (maximum data recording capability). Operating time increases with lower sample rates. Figure
11 illustrates the expected continuous logging time versus sample rate.
The RTC continues to operate from the battery when the device is “off”. The RTC should be
reinitialized if the battery is removed or completely depleted (see ection 2.4).
Gulf Coast Data Concepts Page 8 X16-4, Rev B
The data logger may draw up to 250mA from the USB supply to recharge the battery.
Plugging multiple data loggers into a USB hub can exceed the power capacity of the hub.
This can cause “brown-outs” of the logger and possibly damage the microSD card.
The logger is always “on” maintaining the real time clock and will eventually discharge the
battery completely after several months. The completely discharged battery will take
additional time to recharge. Keep in a cool (20°C/ 68°F dry environment to avoid damage
of the battery pack.
Figure 10: Battery Pack Connectors
Some X16-4 data loggers are assembled without battery connectors and the battery is
hardwired to the PCB. See the Troubleshooting guide at the end of this document for
further information regarding the hardware differences.

2.4 Setting The RTC
A real time clock (RTC) integrated into the X16-4 determines the time for each line of data recorded.
The RTC is initialized using a user-created text file named “time.txt” that is loaded by the logger upon
booting. The time file method of setting the RTC does not require special communication drivers, so it
can be implemented using a simple text editor. Direct initialization of the RTC is possible but requires
specific device drivers and software from Gulf Coast Data Concepts.
Initializing the RTC with a time.txt file is accomplished as follows:
tep 1: Use Wordpad, or an equivalent text editor, to create a simple text file called
“time.txt”.
tep 2: Enter on the first line the current date and time as “yyyy-MM-dd HH:mm:ss” in
24-hr format. Figure 12 provides an example time.txt file that will initialize the
RTC to 2:26:30 pm June 16, 2014.
tep 3: ave this file to the root directory of the micro D card (same location as the
Gulf Coast Data Concepts Page 9 X16-4, Rev B
A 5v supply via the USB connector provides extended operation of the device independent
of the internal battery. Add “rebootondisconnect” to the config.txt file so the logger will
automatically switch to internal battery when the 5v is removed. Common 5v power
adapters used for consumer electronics can provide the required 5v supply but most USB
battery packs are not compatible with the X16-4. The logger consumes very little power
and “smart” USB battery packs will turn off when the power consumption is too low.
Figure 11: Expected Battery Life

config.txt file) and close the text editor.
tep 4: Remove the logger form the PC. The logger will automatically find the time.txt
file and intialize the RTC with the time stored in the file. The file is deleted after
initialization.
The RTC maintains ±50ppm accuracy (-40°C to +85°C), which means that the accuracy may drift
about 4 seconds every day. The RTC is powered by the battery at all times, even when the logger is
“off”.
2.5 Status Indicators
ystem status is indicated by the two LEDs located near the U B connector. The blue LED indicates
system operation and blinks once per second to indicate a properly operating system. The blue LED
blinks when the X16-4 is recording data, in standby mode, or is connected to a computer via the U B
port. The red LED blinks when data is written or read from the micro D memory card. In data
logging mode, the period at which the red LED blinks depends on the sample rate and other
configuration settings. The LEDs will flicker during user initiated shutdown. The “statusindicators”
tag in the configuration file turns off or changes the brightness of the status indicators (see section
3.2.4.10). The red charge indicator LED is located on the reverse side of the circuit board and
illuminates when charging is in process (see Figure 13). The charge indicator LED will turn off when
the battery is fully charged. A fully discharged battery will charge in about 2 hours. A blinking charge
indicator LED means there is a problem with the lithium-polymer battery pack.
Gulf Coast Data Concepts Page 10 X16-4, Rev B
Initializing the RTC ensures that the start time and individual time stamps can be
correlated to an absolute time – the year, month, day, hour, minute, second, and fractional
second. An uninitialized RTC or reset of the RTC will lead to indeterminate start time
recorded in the data file header.
After unplugging the logger from the USB port, the logger will load the config.txt file and
time.txt file, if present. Therefore, there is a delay between when the time.txt was created
and when the logger actually loads the time information. For most applications, this simple
method of initializing the clock results in sufficient accuracy.
Initialization of the RTC is limited to +/-1 second. The RTC register that handles the
fractional seconds counter is not accessible so the initialization process can not reset the
seconds to an even value.
Figure 12: Example Time Entry in time.txt File

2.6 System Configuration Options
The X16-4 is configured using a set of tags and settings stored in a text file named “config.txt”, which
is located in the root directory of the micro D card. The system reads the configuration file at boot
time. Table 1 lists the configuration file tags. Tags that require a setting must be followed by an equal
sign (“=”) and an applicable tag setting. A line finishes with a newline character. Tags are not case
sensitive. Tab and space characters are ignored. Lines starting with a semicolon (“;”) are treated as
comments and ignored by the system. The system will use default settings if the config.txt file is not
found.
Table 1: Configuration File Tags and Descriptions
Tag Valid Settings Default Desc iption
deadband An integer between
0 and 16384
0 ets the deadband to a range expressed in “counts”.
A new sample is recorded if any sensor axis
exceeds the previous recorded reading by the
deadband value
deadbandtimeout An integer between
0 and 16384
3 pecifies the period in seconds when a sample is
recorded regardless of the deadband setting. This
feature ensures periodic data is recorded during
very long periods of inactivity.
dwell An integer between
0 and 65535
1 The number of samples recorded after a deadband
threshold triggered event
microres - Off The presence of this tag sets the device to record
time stamps with 0.1ms effective precision.
rebootondisconnect - Off The presence of this tag causes the system to start
recording after disconnect from a U B port.
samplesperfile An integer greater
than 0
90000 The number of lines of data per data file before a
new file is created
samplerate 12, 25, 50, 100,
200, 400
100 ets the rate at which data is collected and recorded
to the micro D card.
starttime and stoptime ee section 2.6.8 - Defines when to start and stop recording
stoponvusb - Off tops data logging if 5v U B power is present (see
section 2.6.9)
statusindicators “Normal”, “High”,
“Off”
Normal LED status indicators can be activated with normal
brightness (Normal), activated with high brightness
(High), or completely deactivated (Off).
Gulf Coast Data Concepts Page 11 X16-4, Rev B
Figure 13: LED Status Indicators

2.6.1 deadband
“deadband” defines the minimum difference between recorded sensor readings. A new sample from
the accelerometer sensor must exceed the previous recorded reading before the logger records the data.
The deadband setting is expressed in "counts" units and is applied to the output of each axis. The
deadband value can be set to an integer between 0 and 16384. The deadband function is an effective
way to reduce the amount of data collected by defining the granularity of the data.
The deadband functions as a event threshold limit when used in conjunction with the “dwell” feature.
Figure 14 illustrates the deadband feature filtering out small changes in acceleration from the recorded
data. Only when the deadband limit is exceeded will a new data sample be pushed to the file. Note
that this feature will result in samples with inconsistent time periods. Therefore, the data sets should be
re-sampled to establish uniform time periods.
2.6.2 deadbandtimeout
“deadbandtimeout” defines the period in seconds when a sample is recorded by the logger regardless of
the deadband setting. This feature ensures periodic data is recorded during extended periods of
inactivity. A valid setting for the deadbandtimeout is an integer between 0 and 16384.
2.6.3 dwell
Use “dwell” together with “deadband” to create an event trigger configuraion. The “dwell” tag defines
the number of consecutive samples recorded at the set sample rate after a deadband threshold event.
Gulf Coast Data Concepts Page 12 X16-4, Rev B
Figure 14: Graphical Illustration of the Deadband Feature
Do not use the Windows Notepad editor because it does not terminate new lines properly.
GCDC recommends Windows Wordpad or Notepad++ to edit the config.txt file.

The deadband threshold event occurs when a sensor reading exceeds the last recorded value by the
deadband setting. A valid dwell setting is an integer between 0 and 65535. ee section 2.7.2 for an
example implementation of the deadband/dwell features.
2.6.4 microres
The “microres” option sets the device to record time stamps with 0.1ms precision. In micro-resolution
mode, the time stamps are recorded as XX.YYYYZZ where XX are seconds, YYYY are 0.1
milliseconds, and ZZ are spurious digits beyond the precision capability. The micro-resolution option
should be implemented at sample rates greater than 200 hertz to provide the best timing precision.
2.6.5 rebootondisconnect
The X16-4 incorporates an on/off button for initiating and terminating the data recording process. Data
recording is automatically started upon disconnect from a computer U B port if the tag word
“rebootondisconnect” is included in the configuration file.
2.6.6 samplesperfile
“samplesperfile” defines the number of data lines each file can have before a new file is created. This
tag controls the size of the data files into easily manageable lengths for later processing. This setting is
loaded as a signed 32-bit integer, which can translate into very large data files. The user should
exercise caution before setting large files and test the end-user software application for data limitations.
Gulf Coast Data Concepts Page 13 X16-4, Rev B
Figure 15: Graphical Illustration of the Dwell Feature
Micro-resolution is best suited for applications requiring precise timing, such as vibration
analysis, and is recommended for sample rates above 200 Hz. The standard timing
precision (default of 1 milli-second is suitable for most general applications, such as
monitoring human motion.

2.6.7 samplerate
The “samplerate” tag defines the data rate in Hertz, or samples per second. Valid sample rate settings
are 12, 25, 50, 100, 200, and 400 Hz. ee section 4.1 for special features regarding the sample rates.
2.6.8 starttime and stoptime
The X16-4 starts and stops data recording based on the times defined using the “starttime” and
“stoptime” tags. The times must be in “MM HH DD” 24-hr format with the three entries separated by
a space. Entries marked with “*” operate as a wild card. The X16-4 continues to record after the start
time unless defined otherwise by the stoptime tag. Note that the configuration option does not include
the month. Example timing configurations:
Example 1: On the 15th day, start recording at 12:30pm and
stop recording at 6:00pm.
starttime = 30 12 15
stoptime = 00 18 15
Example 2: tart recording at the beginning of every hour
and stop recording 45 minutes later.
starttime = 00 *
stoptime = 45 *
2.6.9 stoponvusb
The “stoponvusb” tag stops data logging operations when a 5v supply is detected on the U B
connector. Without the stoponvusb option (default), the device switches power from the internal
battery to the U B 5v and continues to log data.
2.6.10 statusindicators
The brightness intensity of the LED status indicators is defined using the “statusindicators” tag and
valid settings of “normal”, “high”, and “off”.
2.7 Example Configuration Files
2.7.1 Example A
The following configuration records data at 100 hertz. Deadband and deadbandtimeout are set to zero
so the logger will record constantly at the set sample rate. Each data file is 90,000 lines long, which is
15 minutes of data. The status indicators are set to high brightness. The logger is activated with the
on/off button (notice “rebootondisconnect” is not active).
Gulf Coast Data Concepts Page 14 X16-4, Rev B

2.7.2 Example B
The deadband and dwell settings configure the device to record at least 5 seconds of data when a
change greater than 0.1g is detected. The deadbandtimeout setting forces a sample write every hour.
2.7.3 Example C
The logger must be turned on with the on/off button. It will enter a standby mode (blue LED blinks)
while it waits for the start time. The logger will start recording at 10:30am and turn off at 2:00pm. The
logger will record constantly at 400Hz and create 51 data files in the 3.5 hours. The micro-resolution is
activated to provide the best timing precision at the 400 Hz sample rate.
Gulf Coast Data Concepts Page 15 X16-4, Rev B
Figure 16: Configuration File Example A
;Example X16-4 config file
;set sample rate
;available rates 12, 25, 50, 100, 200, 400
samplerate = 100
;record constantl
deadband = 0
deadbandtimeout = 0
;set file size to 15 minutes of data
samplesperfile = 90000
;set status indicator brightness
statusindicators = high
;rebootOnDisconnect
;see X16-4 user manual for other config options
Figure 17: Configuration File Example B
; Example X16-4 Config file
; set to 25Hz
samplerate = 25
; trigger at 0.1g
deadband = 100
; record 5 seconds of data
dwell = 125
;force a write ever hour
deadbandtimeout = 3600
; set file length
samplesperfile = 30000
; LEDs on
statusindicators = normal
Figure 18: Configuration File Example C
; Example X16-4 Config file
; set to 400Hz
samplerate = 400
; activate precision timing
microres
; record constantl
deadband = 0
deadbandtimeout = 0
; set file length
samplesperfile = 100000
; set logger to turn on with clock
starttime = 30 10
stoptime = 00 14
; LEDs on
statusindicators = normal

3 Data Interpretation
3.1 Data Files
The X16-4 creates a new data file when the system is booted or when the maximum number of data
lines is reached in the previous data file. A system boot condition occurs when the on/off button is
pressed, 5v power is restored to the system via the U B connector, or when the X16-4 is removed from
a computer U B port with the “rebootondisconnect” feature enabled. Data files are placed in a folder
named “GCDC” and are named data-XXX.csv, where XXX is a sequential number starting with 001.
The system will create up to 999 files. At the beginning of each file, a header is written describing the
system configuration and the current time when the file was created. Figure 19 represents an example
data file.
3.2 Data Format
Data is written to files in comma separated text format starting with the file header information and
followed by event data entries. Table 2 lists the valid header tags, although not all tags may occur in
the header. Each data line contains a time entry and the raw accelerometer sensor readings from the X,
Y, and Z axes. The time entry is seconds elapsed from the start time recorded in the header. Add the
elapsed time to the start time to determine the complete date and time of the sample.
The last line of the final data file records the reason for the termination, such as “shutdown: switched
off”, “shutdown: low battery”, “shutdown: max files exceeded”, “shutdown: vbus disconnect”, or
“connected to computer”. The line is designated as a comment with a semicolon (“;”).
Gulf Coast Data Concepts Page 16 X16-4, Rev B
Figure 19: Example Data File
;Title, http://www.gcdataconcepts.com, X16-4, Analog Dev ADXL345
;Version, 1110, Build date, Dec 30 2015, SN:CCDC1016D9857FA
;Start_time, 2016-05-11, 10:15:24.390
;Temperature, -999.00, deg C, Vbat, 3804, mv
;SampleRate, 100,Hz
;Deadband, 0, counts
;DeadbandTimeout, 0,sec
;Headers, time,Ax,A ,Az
0.163,10,24,-2054
0.173,21,28,-2063
0.183,17,12,-2090
0.194,3,7,-2097
0.204,30,5,-2061
0.214,24,24,-2061
0.224,17,26,-2082
0.234,44,16,-2063
0.245,19,33,-2072
0.255,-2,26,-2093
0.265,39,3,-2061
A short gap in data may occur between sequential files as data is purged from the cache
and a new file is allocated on the microSD card.

Table 2: Data File Header Tags
Tag Desc iption
Deadband A new sample from the sensor must exceed the last reading by the
deadband value
DeadbandTimeout The period in seconds when a sample is recorded regardless of the
deadband setting
Headers The names of each column of data in the file
ampleRate Rate at which data is recorded to the micro D card
tart_Time The current time when the data file was created
Temperature Not supported on X16-4, reports -999
Title The name of the U B Accelerometer X16-4 unit and sensor type
Vbat Battery voltage measured at the file start time
Version The version control information of the firmware, including unique
serial number
3.3 Data Conversion
3.3.1 Time Stamps
Each sample starts with a time stamp, which is the seconds elapsed from the start time listed in the file
header. Add the time stamp to the start time to determine the complete date/time of each sample.
The time stamp calculation is incorporated easily into a spreadsheet, such as Excel or Calc. First, open
the data file in a spreadsheet and parse on the comma (“,”) deliminator. Most spreadsheets will
automatically parse the data using the “,” character. The parsing operation will separate the start_time
into two cells – date and time. Use the “trim” function to strip the white space around the date cell and
use “concatenate” to combine the text into a new start date. The spreadsheet will automatically format
the new text into a date. Next, divide the time stamp entry by 86400. This converts the time stamp
into a value compatible with the spreadsheet date functions. Finally, add the new time stamp to the
new start date and a complete data/time is generated. Format the column as a “time” category and
include the trailing “.000” to present the millisecond precision.
Gulf Coast Data Concepts Page 17 X16-4, Rev B
Figure 20: Time Stamp Conversion Method