Logging Signals
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Logging Signals |
Logging provides a way to save signal data without the message data bytes and IDs.
The Logging screen (Figure 1) is opened using the Vehicle Spy Measurement main menu. Last Update:
Monday, November 17, 2008
Logging uses signal groups much like the Signal Plot and Signal List views.
Signal groups are selected with the "Signal Group to Log" drop down.
To change the signals in that group, click on "Select Signals" 
.
The "+" and "-" buttons add and remove signal groups.
Logging Setup 
Click on the "Log this signal group" checkbox to enable the Logging feature.
The next option to set is the Log Rate.
This determines how often the most recent values of the signal group are written to the file.
Enable "Save when data changes" to only create new entries when the signal data has changed.
This can help keep file sizes smaller.
The next field to enter is the name of the log file under "Log File".
The "Log File Creation Options" drop down gives options regarding new file creation, overwriting files, or appending to an existing file.
The last option in this section is to "Ignore formatting on signals and save as analog values".
This option will save the analog values without the specified formatting setup for the signal.
Start Logging 
The options in this section are used to specify when to start the capture.
Logging can be started automatically when Vehicle Spy starts or when an equation evaluates as true.
If a start equation is selected, click the equation button, 
, and build it using the Expression Builder.
Signal values before the start trigger can also be collected.
The "Enable Pre Start Collection" option allows for a predefined number of seconds to be pre-captured before a trigger expression is true.
Stop Logging 
Stop Logging options are similar to Start Logging options.
Stop Automatically will stop saving data when Vehicle Spy is stopped.
A Stop Equation can also be set using the "Stop on equation" option.
With this enabled, data logging will stop when the equation is true.
The last option is to stop after a specified time.
Log files can also be zipped as they are saved to reduce storage space.
Invalid Signal Handling 
An invalid signal can occur when signal data is cleared in a function block or when Vehicle Spy starts before signal data is available.
Vehicle Spy has a few options to handle these conditions.
The first is to use the last valid value.
Another is to leave a blank space for that value.
The last option is to replace the invalid value with a known value.
This option is handy if other programs are going to chart or graph this data.
Blank or text entries can be replaced with a value that is still able to be graphed, but is known to be invalid data.
When Logging is running, its status is displayed in the upper right corner 
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Data can be viewed while it is being collected by using the View Data button
Figure 1: The Logging screen.
Vehicle Spy Documentation - (C) Copyright 1997-2011 Intrepid Control Systems, Inc.