Although originally developed for the automotive industry, CAN (Controller Area Network) fieldbuses have been used in a wide range of industrial and commercial applications. We now find CAN in use at CERN within the experiment sectors for the control and monitoring of low level devices such as Wiener/ISEG power supplies or the ATLAS ELMB.
These CAN nodes are distributed over buses that are interfaced to the computer via PCI, USB or Ethernet CAN interfaces.
The control and monitoring data of the devices on the CAN buses is handled by WinCC OA, which communicates via a native OPC client to a vendor specific OPC server. The OPC server then communicates over CAN with the physical device concerned.
The OPC DA servers were originally written for a CERN defined set of CAN interfaces, mostly from Kvaser AB, making use of the vendor specific hardware APIs.
To be able to use other CAN interfaces within this control context, it was necessary to write 2 wrappers DLL that would map between the original vendor (Vendor 1) API used in the OPC DA server and the new hardware API from new CAN interfaces from SysTec and Analytica (Vendor 2). The compatibility between the components is shown in the table below.
|Wrappers DLL||ELMB OPC DA Server||Wiener OPC DA Server||ISEG OPC DA Server||CAN interface type|
|AnaGate Wrapper DLL||✓||✓||x||
AnaGate Ethernet-CAN models
|SysTec Wrapper DLL||✓||✓||x||
SysTec USB-CAN models
|N/A||x||x||✓||PEAK USB-CAN models|