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Using the Internal Real-Time Clock on cRIO-901x Controllers

Hardware: CompactRIO>>Controllers>>cRIO-9012, CompactRIO>>Controllers>>cRIO-9014

Problem:
In the manual for the cRIO-901x Controllers it states the following: "The system clock of the cRIO-9012/9014 is synchronized with the internal high-precision real-time clock at startup. This synchronization provides timestamp data to the controller. You can also use the internal real-time clock to correct drift of the system clock." How can I use the internal real-time clock to correct drift of the system clock?

Solution:
To use the internal real-time clock to correct drift of the system clock add the following lines to the ni-rt.ini file for the controller.  You will need to FTP this file onto a Windows machine, make the changes, and FTP the modified file back to the controller.  After updating the ni-rt.ini file, the cRIO-901x controller will automatically implement the GPS drift-correct based on the input Pulse-Per second input.

[Time Sync]
source.rtc.enable=True
source.dio.enable = True
source_priority=dio;rtc;
source.dio.hz = 1.0

You can also set the expected frequency of the input. The default is 1.0 Hz. For example, If 2 Hz is the expected frequency change the last line to source.dio.hz = 2.0.  Note, that if the PPS signal is lost or the error is greater than 10% off from the expected frequency, the drift-correction measurements will not be used to correct the clock time on the Embedded Controller.



Related Links:

KnowledgeBase 493C8ELX: Configuring CompactRIO Real-Time Controllers to Synchronize to SNTP Servers
KnowledgeBase 493BIHLX: Using the SMB Connector for Digital I/O on cRIO-901x Controllers

 



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Report Date: 08/27/2007
Last Updated: 09/19/2008
Document ID: 4CQFC9LX

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