Hello,
I am testing out using an EIOC as a OPC UA Client in a redundant setup in order to interface with a set of OPC UA Servers (Kepware). Physically, the architecture looks like:
The Kepware servers are mirrored with the same configuration. Their goal is to provide redundant access to field device data, but I do not want them both to communicate to the field devices at the same time as it will overwhelm the radio network the devices are connected to.
According to DeltaV BOL, the EIOC supports the following redundancy models:
DeltaV OPC UA redundancy support
DeltaV OPC UA supports redundancy as follows:
KepServer handily tells you how many clients are connected to it and how many points they are consuming. When I initially configure a PDT on the EIOC, I can tell that it is acting in Cold mode: Both KepServer instances show clients but only the primary shows consumed points. Once I do a fail over test (such as unplugging the network port on the primary KepServer server), the EIOC fails over correctly and starts actively getting data from the standby server.
However, once the primary server comes back online, the EIOC begins to poll data from it again and goes into Warm mode and stays there. The only way I've found to get it back to Cold mode is to download the EIOC port (or the individual PDT's).
I don't care if the EIOC fails back over to the primary server, but I need it to act correctly in regard to Cold failover. It is also possible that I am mis-understanding how Cold vs Warm fail over is supposed to work, but I am under the impression that my setup is legitimate for a cold failover set.
Is there a way to force the EIOC to remain in Cold mode? Is there a better way to engineer my setup to meet the goals above?
Thank you,
Dave