I've got a customer who wants us to look at changing the control structure of a small line, and I can't readily find answers to some of my questions.

The potential plan is this. Use a single node with Steeplechase VLC to control the line. This part is straightforward and easy enough to do.

The Steeplechase package comes with a Ci-tect HMI which can be used for the control node. This part is also easy enough to do.

The next part is where I don't have a ready answer. Can we use a VB application on 4 operators nodes as slave HMI's rather than purchase additional Ci-tect licenses? The HMI configurations for those stations is extremely simple, and the VB development costs would be less than half of just the license cost for the HIM runtimes.

My questions are whether the Ci-tect package which is included in Steeplechase is a full-blown package or restricted package? Can that node serve as an OPC server to remote VB clients? I don't know if either Steeplechase or Ci-tect can act as an OPC server. (It's been several years since I've worked with either one, and I know they have to have moved along.) If neither the Ci-tect nor the Steeplechase instance can serve as an OPC server is there a third party OPC server which could run on the control node and handle the clients? If OPC won't work, would something older like DDE work with Ci-tect. (I can't imagine the Steeplechase VLC can support DDE.)

Has anyone ever tried something like this? I know this sounds complicated for what I describe as a "simple" line, but that's what I've been asked to produce.

Thanks in advance,
Michael
--
Michael R. Batchelor - Industrial Informatics & Instrumentation, Inc.
Linux is like a wigwam...
No windows, no gates.
Apache inside.

 

Michael,

I do know that the Steeplechase VLC can act as an OPC server as we have a client who has connected to it with VB successfully. To make the connection in VB he used an activeX control he dropped into VB and connected to the remote VLC via OPC and DCOM. The activex he used is found at "www.opcactivex.com":http://www.opcactivex.com . I don't know if you need anything special on the VLC to expose OPC or not (i.e. separate purchase) but I'm sure if you contacted them ( "www.entivity.com":http://www.entivity.com ) they could tell you.

Don't know if Citect can be an OPC server in addition to being a client - if they could then you could connect to it with VB using the same approach.

John Weber
Software Toolbox

 

Michael, if you are talking about Citect from CiTechnologies, which I believe you are, then yes you can do what you are thinking about. Citect can act as on OPC server as of version 5.2. But if you are using VB it might be easier to use Citects API (CTAPI.dll). With the API you can read in all tag values and right tag values. So this is ideal for a small remote station. I have a small demo VB6 project that reads and writes to tags on a Citect server, if you would like a copy let me know.

Please contact me if you need any other help.



Thanks,

Eric Johnson
ACES
[email protected]
"It's all 1's and 0's Baby!"

 

Thanks, but I'm a little confused about using an AX control to make the OPC connection. In the past we've always just made the calls directly, which is granted a pain in the butt, but works.
Can the AX control let us do something easy like configure a tagname dictionary without lots of work? I'd buy that.

MB

 

Eric,

I think Michael was worried that the version of Citect that is bundled with Steeplechase doesn't necessarily have the full functionality of the full blown Citect package, which is a valid concern. Back when I was looking at Steeplechase they were using FIX MMI as an MMI and did not necessarily have all the features or stay up to date with the latest features from Intellution. This was due to the special licensing arrangements Steeplechase had/has with its component vendors.

At that time, they *did* have an option to buy the communication API/DLL to read/write data from the real-time subsystem. In that case you could write your own MMI in VB/VC++/what have you. I believe you could run completely without the FIX MMI, but that was several years ago.

I don't know what their current policy on the roll-your-own MMI is, but if it's the same way it was, you should be able to do whatever you want. It should peacefully co-exist with the CiTect MMI, so you can have both, if they did things right.

I was pretty happy with the technical abilities of the Steeplechase folks and the fact we didn't use it was more a problem with flowchart control (which wasn't the best fit for us) than with the performance of the product.

Steeplechase merged with Think-n-Do, their main flowchart programming competitor, under Entivity ( "http://www.enablingproductivity.com/":http://www.enablingproductivity.com/ ) . I don't know what the ramifications of that merger was, either.

Rufus

 

Michael,

I used the Steeplechase VLC from Jan, 1998 thru Jan 2002 and found it has a slow DDE server good for quick links to an Excel spreadsheet, a DLL library called Data-Express which is much faster and easily used with Visual Basic 5.0 and up as well as C++.

The most recent addition was an OPC server which can be accessed with Visual Basic 6.0 and VB script for Excel and example code is available.

Things have sort of gone downhill since they were purchased by Entivity and a lot of the technical support guys I knew there have left.

The Citect HMI is a "lite" version and not object oriented, so any database work for recipes had to be done through the "Cicode" programming language and instruction manuals on using advanced features were not available. It was quicker to use than Visual Basic, but not as flexible.

The distributor I worked for dropped the product and eliminated the Steeplechase Support Specialist position I was trained for, so I havn't had an opportunity to review any version past VLC 5.2x but I really enjoyed using it.