Issue
What is the maximum number of trend logs in a SmartX IP Controller?
What is the maximum number of trend log records in a SmartX IP Controller?
Product Line
EcoStruxure Building Operation
Environment
Building Operation Multi-purpose Controller
Cause
SmartX IP controller free object system memory is shared between objects and data in your application. There are no specific limits on the number of objects and/or trend logs that you can create.
Several factors impact memory consumption:
- Every object added consumes a fixed amount of memory
- Memory is shared between objects and data. Adjustments to description fields or trend log buffer sizes will also impact the amount of memory consumed.
- Different controllers have different amounts of memory to start from. RPC controllers have roughly half of the memory of an MPC.
- Changes to EBO 3.X will also change the memory consumption, so upgrading your system may skew the memory consumption larger than it was in previous versions.
Resolution
After adding trend logs to the device consult the Free object system memory entry in the device report since this will help determine how much free memory is available.
Trend log buffers are pre-allocated on creation of the trend object.
The other place to find how much free memory the device have is in the device property page. This value can be put in a watch window, trended, or even bound to a low-limit alarm.
If the amount of free memory drops below 50 Kbytes, that is critically low available memory. A better target is to try to preserve 50% of available memory. Based on empirical testing, estimates of memory available inside a blank controller are:
- MP-C: 1890 Kbytes
- MP-V: 1780 Kbytes
- RP-C: 1115 Kbytes
It is important to not overload the controller because the remaining memory can also be used for COV subscriptions (the last line in the table above). If there is no memory available, then opening a graphic which creates COV subscriptions could overrun memory or operate very slowly
