OPC Client

Hi,

OPC client get data from OPC Servers, fine, but from OPC client how can we get data? We can get data only through SCADA? If yes, is this OPC Client concept is made exclusively for SCADA?

If I want the above data to be used in a VB script, taking data from OPC Server or OPC Client will have the same headache?

Rgds,
Randheer-P

Randheerp,
In the future you would be better off just asking about what you are trying to accomplish at the end. For example, "How do I log data from my Modbus PLC to a Microsoft SQL Server database". More details about your system and requirements would be better yet. Forum members would then understand what you need, and be able to best offer suggestions. My recommendation to your other posts remains your best option, in my opinion.

http://www.plctalk.net/qanda/showthread.php?t=74818
http://www.plctalk.net/qanda/showthread.php?t=52709&page=2

To answer your latest questions - there are many options:
1. OPC is not required to talk to a PLC. It is a standard for interoperability.
2. Getting data from an OPC client in general is not really a meaningful question. The OPC client does whatever the program was written to do - change colors on the screen, send text messages, write to a database, whatever.
3. VB script could run in a standalone product or an OPC client

Heck, you could write a program that talks directly to your PLC via modbus then logs the data to a SQL server in almost any language. Good luck with that, though.

OPC Clients are typically embedded in applications such as HMI and data collection systems, SCADA, etc.

They are essentially the middle man between the application (HMI, SCADA, etc) and the OPC server. They translate requests from the application and send it to the OPC server (based on the standards it is compliant with). It also translates info back into the native format of the application you are working with (HMI) so that you can do useful stuff with.

I am not sure if I answered your question or not.