Calculating the router memory

Memory for the BACnet object representation in the PLC is taken from the router memory. The default setting in TwinCAT is 32MB and may need to be increased in case of a larger BACnet object database. The log-buffer of Trendlog or Eventlog objects is taken from the router memory as well.

As an average the properties of BACnet objects require 20 KB each.

To reserve some memory space for other purposes, the library raises an error condition when more 60% of the available router memory is requested by the BACnet library. In this case, further BACnet objects are not created anymore so the project database may be incomplete.

On Windows Embedded compact (Windows CE) systems, the maximum router memory is limited to 200MB. On Big-Windows (Windows 10) or BSD the router memory depends on the non-paged pool. E. g. if the total non-paged pool is 1 GB, the router memory may be increased to 600-700MB. Please note, increasing the router memory may require a reboot of the PLC.