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Calculation of Controller memory usage for controller log ( controller logging )


How to calculate total memory required for controller to store logging information for the required duration.


NetController (CX9900, CX9940, CX9680, bCX9640)

InfinetController (i2xxx)

BACnet Controller (bCX4040, bCX9640, b3xxx)


Need to know how much memory is needed per point to determine the maximum number of entries and minimum interval time that the controller can use.


The general equation of calculating memory use for controller logging is as below;
* Memory usage per point = { 8bytes + (4bytes * NumberOfLog) }
In addition to that, each controller requires minimum 1~2KB of freemem after the controller logging memory allocated. 

Regarding the log interval, if the point is being logged for controller only, you can set the interval in seconds unit.   But if you configure the point for ExtendedLog as well, the logging interval should be in minute unit.

Again, if you have many points with one minute interval for Extended logging, it will affects the performance of the Cyberstation and also increases the size of ContinuumDB dramatically in short period of time.

In this case, please consider to increase the log interval to 5 ~ 15 minutes for Extended logging.

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