adccommunitymod (AutomationDirect) asked a question.
Created Date: May 11,2001
Created By: mikesobo
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I am testing out using Directsoft data server with Wonderware Intouch. The problem that I am having is that it appears that all the DSData server OPC tags can only be seen as a signed double word integer, regardless if they are a discreet coil or not. In addition to being conufusing in tag names, it seems that there would be alot more overhead passing that large of a data item as opposed to a discrete bit for most of our tags. Our current project uses over 2000 tags and we want to get better performance than DDE can provide. There isn't much information on implementing OPC, so any hints would be greatly appreciated. Thanks
Created Date: May 11,2001
Created by: mikesobo
I am testing out using Directsoft data server with Wonderware Intouch. The problem that I am having is that it appears that all the DSData server OPC tags can only be seen as a signed double word integer, regardless if they are a discreet coil or not. In addition to being conufusing in tag names, it seems that there would be alot more overhead passing that large of a data item as opposed to a discrete bit for most of our tags. Our current project uses over 2000 tags and we want to get better performance than DDE can provide. There isn't much information on implementing OPC, so any hints would be greatly appreciated.
Thanks
Created Date: May 12,2001
Created by: Russ
Hi Mike,
There have been several past discussions about OPC here in the forums - if you do a search on "OPC " you should be able to find them.
For example, check out http://forum1.automationdirect.com/board/Forum1/HTML/000159.html It has a posting I did on some basic OPC resources, as well as an ASP code example.
Hope this helps, and good luck with your project!
Regards,
Russ O 'Rourke
Created Date: May 19,2001
Created by: Mike McClanahan
Unfortunately you are limited to this by the OPC standard for the data being returned. Since it is an open protocol, someone decided that all data coming back must be standardized to some type. you should not be having any problems with speed using the DSData OPC Server for this many tags. We timed ours for 780 points on startup and it took less than 1 second over a 10 MBit ethernet connection to initialize the values of all points. Once the points were loaded the change in state was passed to us immediately on the state of the point being changed.
Mike McClanahan
Created Date: May 21,2001
Created by: Ray Kissane
We have not been able to get a very good speed with the DS Data. We are using VB6 to make a simple HMI and we actually got better speed with DDE and VB3. We have since changed to a differnt server, KEP server EX and are getting a tremendous speed increase. I think Wonder Ware has license Eldrigdes server so you may want to try that one also.
Created Date: May 21,2001
Created by: Russ
I agree with you Ray. Just as a general observation, KEP's server is roughly 3 times faster in DDE transactions than the DSData server is. However, in defense of the DSData product, speed and acceptable performance is a relative thing. The DSData server could probably be tuned for better performance, but it does work, is compatible with the DirectSoft programming environment and at $295 is roughly a third of the $795 KEP wants for it's package, and unlike KEP, provides DirectNet and k-sequence serial and ECOM protocols together.