An inter-application communications control architecture, referred to as the Communication Fabric (or ComFab for short), is included with the PSCAD V5 product. In all prior windows versions of PSCAD going back to V3, Transmission Control Protocol/Internet Protocol (TCP/IP) had been the only protocol used by EMTDC and PSCAD to communicate during a simulation.
With the advent of parallel and high-performance computing and the launching of multiple, inter-linked EMTDC simulations running in parallel, the communication overhead imposed by the TCP/IP protocol was found to be a serious speed impediment. Consequently, new means of communication were implemented to overcome this issue.
ComFab is an internal mechanism that acts as a simulation process communications manager. It can be utilized by third-party software, via the Co-Simulation API, to communicate with PSCAD and EMTDC, provided that protocols are adhered to. ComFab supports two types of communication protocols: The legacy TCP/IP (default) and Shared Memory. Description of these are given below.
Mode |
Restrictions (Scalability) |
Performance |
Details |
TCP/IP |
None |
Local – 20 ms Remote – 400 ms |
This is the legacy mode of communication between PSCAD and EMTDC. Prior to PSCAD V5, this was the only mode available. |
Shared Memory |
Single Computer |
Local – 1-2 ms |
Shared Memory is memory that may be simultaneously accessed by multiple programs (i.e. in our case, PSCAD—EMTDC, and/or EMTDC—EMTDC) with an intent to provide communication among them. Shared Memory reduces the communication overhead to a near negligible level, but is best suited for running simulations on a single, multiple-core computer. |
The ComFab is intelligent enough to select the best protocol for your local configuration, and as such is always enabled and functions seamlessly in the background.