Hello Everyone,

I am evaluating the data logging features of PV450 for our system. I intend to use this feature as a blackbox and record data ( time stamp: faults / conditions ) on certain events of the system. The system where this display will be used is a proprietary system and NOT a typical J1939 / Engine bus.

My concerns and also some that I need to answer to our customers.

1. Primary concern, after a prolong usage will the corruption of data logging sectors affect the device functionality. Where does the data logging file reside ? on the same flash chip with the rest of the OS/filesystem ? separate sectors on the flash chip reserved exclusively for data logging ?

2. The PV 450 datasheet mentions expandable Flash size to 8GB. Is there a removable flash media (SD card) inside the device ?

3. Can the log file be made to overwrite once it reaches the end ? Like a circular buffer.

4. Is there any data that can suggest how long before the data logging begins to corrupt ? Any experiments done at FW Murphy ?

I need to provide our customers the life expectancy of the data logging / device.

Thank you,
Sandeep Sirpatil

Mr. Sirpatil,
Here are answers to your questions regarding the PV450 Data logging features. Please note the responses in red.

I am evaluating the data logging features of PV450 for our system. I intend to use this feature as a blackbox and record data ( time stamp: faults / conditions ) on certain events of the system. The system where this display will be used is a proprietary system and NOT a typical J1939 / Engine bus.

My concerns and also some that I need to answer to our customers.

1. Primary concern, after a prolong usage will the corruption of data logging sectors affect the device functionality. Where does the data logging file reside ? on the same flash chip with the rest of the OS/filesystem ? separate sectors on the flash chip reserved exclusively for data logging ? It is the same flash chip as the rest of the OS/Filesystem. The filesystem is similar to JFFS2, it is a journaling load levelling file system. This type of file system provides for wear levelling which is designed to increase the life span of flash memory by distributing erasures and re-writes throughout the medium. It also provides for clean up by monitoring and removing old static data. Separate sectors are not reserved for data logging, the data log is stored as a file. Like any flash chip there are limits to the writes, but the flash chip is good for 100,000 erase / write or 10 year data retention. It is a NAND based flash chip.

2. The PV 450 datasheet mentions expandable Flash size to 8GB. Is there a removable flash media (SD card) inside the device ? No. The configuration tool limits the size of the data log file to 32Mb. The data log can be exported to a usb flash stick.

3. Can the log file be made to overwrite once it reaches the end ? Like a circular buffer. Not as a standard feature, BUT it does have a save and clear function. So one can save the log file to usb, then clear it to start over.

4. Is there any data that can suggest how long before the data logging begins to corrupt ? Any experiments done at FW Murphy ? We do an overnight corruption test, there has not been any data corruption seen. Again the chip can provide up to 100,000 writes and retain for 10 years.

In general, the datalogger that is built into the unit can be exported to a flash stick. I think for your application you should think more in these terms.

Thank you for your post,

Sincerely,
John Morgan
Test Engineer
FW Murphy