Adapting the router memory

The main memory is used by TwinCAT/BSD and by TwinCAT (TwinCAT memory). The TwinCAT memory is further divided into the router memory and the PLC memory. The router memory is used for ADS communication and the PLC memory for the actual PLC program including TcConfiguration, mapping and data.

An adjustment of the router memory is only necessary if a large amount of ADS communication takes place and for this reason it becomes necessary to design the size of the router memory accordingly. By default the router memory is set in TwinCAT. The maximum value for the router memory is 1024 MB.

Make sure that the heap memory is larger than the router memory and otherwise increase the heap memory before adjusting the router memory (see: Increase heap memory). This chapter shows how the router memory can also be customized under TwinCAT/BSD.

To do this, the XML file at /usr/local/etc/TwinCAT/3.1/TcRegistry.xml must be adapted as follows:

Path: HKEY_LOCAL_MASCHINE\SOFTWARE\BECKHOFF\TWINCAT3\SYSTEM
Entry: <Value Name="LockedMemSize" Type="DW">{size in Byte}</Value>

Proceed as follows:

---snipped---
<Key Name="System">
      <Value Name="RunAsDevice" Type="DW">1</Value>
      <Value Name="RTimeMode" Type="DW">0</Value>
      <Value Name="AmsNetId" Type="BIN">0542F70C0101</Value>
      <Value Name="LockedMemSize" Type="DW">33554432</Value>
      <Value Name="SysStartupState" Type="DW">5</Value>
      <Value Name="HeapMemSizeMB" Type="DW">1024</Value>
---snipped---