OPC Item/Tag definition in VB6

Hello

I've been using RSLinx OPC Server to read/write tag values to/from a VB6 program, but we've been wanting to move to the ArchestrA.DASABCIP.3 OPC Server as we don't have RSLinx on many of the PC's. ArchestrA is installed as the standard OPC Server for our Wonderware HMI's.

It's only today, after many many dead ends, that I've finally got the VB application sort of working with DASABCIP

With RSLinx, getting to a tag is something simple like PLC_CPS_OPC_FAST.Press_Thickness_SP
however, with DASABCIP, I seem to have to define the fill path to the tag
PORT_CIP.ENB_CLX_Press.BACKPLANE_CLX.LOGIX5000_CLX.Press_Thickness_SP

PLC_CPS_OPC_FAST is defined as a device group in the ArchestrA System Management Console, but no items are defined. However, in the diagnostics, all the tags are available when drilling down into PLC_CPS_OPC_FAST

Is it normal to have to specify the full path to the tag rather than the device group to which it belongs, or are we missing something in our ArchestrA setup?



Thanks for any help you can provide.

Rich

Hello RichBarry! and welcome to the forum to top all tech forums...

While I have no time to directly reply, and no Archestra experience, let me suggest you do a forum search for "RSLinx OPC Archestra" if you have not already done so, and sometimes a Google search will find things here and elsewhere faster too.

That is the best first post I have seen in years by the way...

Paul

Hi, if you look at most servers you will see that format is typical. The OPC Specification left a little leeway on how a server presented OPC items. So neither is incorrect. Most server helo files should provide examples syntax for OPC Items.

Thanks Fred.
The ArchestrA documentation was pretty hopeless in regards to VB6, and I guess that they prefer people to be using Wonderware rather than tapping into the OPC Server with other software.
I've got no problem specifying the full path, but it's a shame that so much time was wasted in finding out this was what was required.

Cheers

Rich

Yes hat is the case with Wonderware although their docuemtnation is usually pretty good.

There is one option in OPC you can use the AccessPaths property on the AddItems method. This allows you to trim the item ID as it were. For example if I had serveral items that were in sub groups Channel1.Group1.Global.Tanks I would set that as the access path for each item. Now lets assume that there are 5 tanks each with a tag named Level, Hi, and Low. I would now only have to us an item name like Tank1.Level, Tank1.Low, and Tank1.Hi.

Hope this helps.