Data storage on programmable WSN node?

[markza]

HI,

I'm doing some research into a potential application, whereby we want to put wireless nodes onto a vehicle and measure certain signals.  However, sometimes that vehicle could leave the area and be out of range for extended periods of time.  During this time, we want to log the sensor data locally on the node until the node is back wintin range of a gateway.

Is this kind of thing possible or not?  

From the datasheet is states "Programmable with the LabVIEW Wireless Sensor Network (WSN) Module: customize node behavior to extend battery life, increase sample rates, save data locally, and perform local analysis and DIO control"

So to me, it looks as though this is in fact possible.  But how much memory space is available for this storage, and what format can you store the data in? IE: text, binary file?    

[Burt_S · Accepted solution]

Hello,

You are correct that this functionality is possible with the WSN platform.  Each node has flash memory available that can be written to by a program running on that node.  The memory size is listed in the node's specifications, but is likely around 250K bytes.  You will need the NI LabVIEW WSN Module in order to program the nodes.  The flash API is very basic and requires you to save the data in raw bytes, and to remember the offset for the beginning of the data.  There is no file API for saving the data.  However, the node is capable of noticing when it is disconnected, logging any samples to flash memory, and then sending all of the logged data via user messages once it reconnects.  I hope this helps!

[markza]

Great, thanks for clearing that up.

[markza]

Also, what is the flash sector size on these nodes?

1K, 4K what?  I can't see anything in the help or specs.  It just says:

User flash size		248 Kbytes
Number of flash erase cycles per sector		100,000

[Burt_S]

Great question.  You are correct that this isn't documented anywhere. 

Using the Config Node "Flash.Number of Sectors" property on the node resturns 62.  This size is the same for the 3202 and 3212, but may change for other nodes.  With 248 Kbytes, and 62 total sectors, each sector should be 4k.

[markza]

Excellent, thanks!

[xinke]

Hi Burt, 

   May I know if there is any online documentation or samples where I can find out more about the flash API ? Thank you very much.

Regards,

Xinke

[Scott_A]

Hey there,

Have you taken a look at User Memory VIs?  What kind of thing were you looking for?

[xinke]

Thank you, Scott. I have resolved the issue.