recondaddy
Member
Hey everyone,
I'm doing a lot of reading, today, about OPC, and I need some guidance.
Here's what I want to do: I want to create an OPC client application in VB.NET that interfaces with the OPC server in RSLinx Classic OEM. What I'll eventually do is monitor a tag value in a PLC and when it goes high, I'll pull a group of PLC tag values into the client and write them to a database.
I'm not yet interested in the nuts and bolts of how I'm gonna do it -- I'm trying to get a high level understanding of OPC so I know where I'm going.
I've set up links to an Excel spreadsheet using RSLinx, before, so I'm familiar with DDE/OPC topics and how to set them up. My question comes in regard to OPC Groups and OPC Items and how they relate to what I'm trying to do.
Am I correct in understanding that an OPC item, in this case, would be the connection to the tag, itself? What role would an OPC Group play in what I'm trying to do? In looking at other peoples' source code, I see them adding OPC Items to OPC Groups. What is the purpose of an OPC Group in the code that I'll write? Will I have only one OPC Group? Several?
I don't even know if I'm asking the right questions. I guess I'm asking how someone with experience would do what I'm trying to do.
Thanks for any help you can provide.
I'm doing a lot of reading, today, about OPC, and I need some guidance.
Here's what I want to do: I want to create an OPC client application in VB.NET that interfaces with the OPC server in RSLinx Classic OEM. What I'll eventually do is monitor a tag value in a PLC and when it goes high, I'll pull a group of PLC tag values into the client and write them to a database.
I'm not yet interested in the nuts and bolts of how I'm gonna do it -- I'm trying to get a high level understanding of OPC so I know where I'm going.
I've set up links to an Excel spreadsheet using RSLinx, before, so I'm familiar with DDE/OPC topics and how to set them up. My question comes in regard to OPC Groups and OPC Items and how they relate to what I'm trying to do.
Am I correct in understanding that an OPC item, in this case, would be the connection to the tag, itself? What role would an OPC Group play in what I'm trying to do? In looking at other peoples' source code, I see them adding OPC Items to OPC Groups. What is the purpose of an OPC Group in the code that I'll write? Will I have only one OPC Group? Several?
I don't even know if I'm asking the right questions. I guess I'm asking how someone with experience would do what I'm trying to do.
Thanks for any help you can provide.