What are the minimal network requirements to execute WinCC OA?
It’s not possible to give a clear answer for this question because the required network resources depends on the size of the WinCC OA project (DPID) and amount of value changes per second.
On big systems with large DPID and a slow network connection between the WinCC OA servers and the remote UI the startup of a WinCC OA panel could take a while because the complete DPID has to be transferred to the UI in the 1st place.
Finally a slow connection could be sufficient when the open WinCC OA panel get’s only very less update information. But a panel which get’s a few 100 msg/sec including alert row could exceed the availed network resources in the same project.
On systems with slow network connection it is recommended by ETM professional control to test the situation from customer site in a test lab. With special vendor software it is possible to simulate a slow network. If the expected amount of msg/sec is known it is also possible to calculate the requirement network resources because a typical WinCC OA message takes around 160 bytes on the wire.
With special circumstances with a small DPID and very less updates per second a WinCC OA project was already released with a modem connection between WinCC OA servers and remote client.
The required network connection between WinCC OA driver and PLC depends also on the updates/second which gets the WinCC OA driver from the PLC. It is also possible to optimize this behavior when features like PollOnUse from the S7 driver are used in a project.
Following data where realized and tested with other WinCC OA projects but those data are no warranty for other WinCC OA projects because as mentioned before every project is different. A test of the WinCC OA project should run with the expected load and a simulated network speed from customer site before the system is deployed on customer site.
In a real project with geographical wide distributed systems a network connection of 4MBit/s and a latency of 700msec between the DRS and DIST connections via VSAT were realized with WinCC OA. In this case the usage of network accelerators from 3rd party vendors is recommended by ETM professional control.
A connection of 512kBit/s and a latency of 50, 300 and 500 ms were also successfully tested in WinCC OA systems with DIST and RDB connections.
For the connection between to redundant Servers a minimum of 100MBit and a very good latency is recommended because a lot of data has to be exchanged between both hosts.