The simple answer of both different is that OPC is the latest open or type of open standard, and the WonderWare presented I/O servers are elder technology. If you are setting up anything new, after that apply with OPC. If you are seeking to set free an old system, use what it requires.
In point of fact, this is not really correct. Wonderware I/O Servers are not old technology and OPC is not new technology. They are basically different technologies. The wonderware I/O servers are utilized for the software of Wonderware; on the other hand, they can also be applied with any program external that supports NetDDE, OPC, and DDE. The newest Servers of DA support communication of OPC. The OPC has been exist quite a while and is according to Microsoft COM. This is not new technology, in actual fact, Microsoft is going away from it and this is one of the reasons the committee of OPC is looking to improve the 'standard'. Regrettably, when you have a lot of companies with their own agendas this transform can be very time-consuming. It is a good documented detail that the OPC crossways a network is not very healthy. The distributed configurations are really on DCOM which can get some modification of settings network.
So the short answer should be, if you are utilizing the software of Wonderware then use a server of Wonderware. The subject communication is performed via TCP/IP which is the majority commonly utilized transport for the communications network. It is also the mainly seamless when it approaches to the security and firewalls. If you require to connect to the Wonderware and a product from third party this can be performed with a Server of DA. If one does not live then it recommends Toolbox of Software which supports the Wonderware Suitelink and OPC.
You are right, however it has found in the 10+ years working with the drivers of the WonderWare as compared to the Server of Software Toolbox TOP, Matrikon, Kepware, which is all OPC compatible, the servers of Wonderware fail to notice the mark including their DA Servers. It would user to buy the InTouch with no IO and pay out better money on IO Servers that operate. Not considering of the OPC problem, almost any server from third party is enhanced than Wonderware's best server. Plain and simple, they stink for the extra $1,000 and more they charge.
The I/O server particular to assured the HMI for example the WonderWare only runs with that software and not anything else. If you also wish for to carry the data into other applications this is not possible. At least not directly, possibly you can plan it through the database of HMI but after that you may require to recompense for more licenses and it will be slower. And it might or might not be possible.
The OPC server is better in the logic that you can take the data to any application, it is including the wonderware, for example the statistics process control, auto tuning, advanced control, process historian, batch etc. There is an approximately endless list of the software that supports the OPC. You can put in this software later on as the application needs to change and grow. You can even transform the HMI at some stage. Or have to diverse the HMI in parallel for whatever motive.
To recognize the benefits of the OPC, how to use it, and what can be performed with it, you can buy and read the book of Software for Automation: Architecture, Integration, and Security.