Citect with OPC Server

[Marie]

Hi all,

I'm trying to communicate between an S7-300 plc and Citect via MPI (CP5611 card). I managed to establish a connection between my PC and my PLC using an OPC Server. I verified that it worked with OPC Scout, from which I can now read and write to the PLC.

Question: How can I use the OPC server as a link between Citect and my PLC?? I know it is feasible but I don't know how.

Or... If you know how to make the connection without using OPC, it would be fine also...

Thanks

Marie

 

[John Gaunt]

Hello Marie,
Personally I don't like OPC. I worked on a large
oil and gas industry project in Scotland a couple of years ago.
That used OPC for Citect communication but I did not like the
very long addresses required for OPC requiring a lot of typing
to set up with several hard to find errors.
As I mentioned in one of your other threads I prefer to use
Profibus for Citect S7 comms but it should be very similar to
set up using MPI.
I will try to attach some writeups I have prepared that I leave
with my customers (mainly in India)
I have another writup but I think it will be too large (5mb)
to attach here. I could email it however.
Regards..........John Gaunt

 

[PhilipW]

I've just finished using Citect to an RSLinx OPC project.

1. Try not to include tags in the Citect database that do not yet connect to a PLC address. It slows down the OPC client something horrid and pages can takes 10's of seconds to re-load. Once all the tags were working, it all sped up to normal response times just fine.

2. There were some obscure OPC initialisation things to get right on the Citect side...sorry but I have forgotten the details.

3. Once you are using OPC the I am guessing that it would be easy to run the Seimens programming software on the same PC and "Copy&Paste" the tags across.

4. Sadly the Citech implementation of OPC does not seem to support the direct "Tag Browsing" feature just yet.

 

[BobB]

4. Sadly the Citech implementation of OPC does not seem to support the direct "Tag Browsing" feature just yet.

I was under the impression that Citect could "read" the tags straight out of the PLC or the PLC software with AB these days. Perhaps it is only the straight RS Linx driver?????

Supposed to be able to do the same with Modicon. Do not know about Siemens.

They have been annoying Omron for access to CX-Server as well but not on the immediate priority list with Omron at the moment. It will happen but the PLC guys all get a bit funny with proprietary stuff. Agreements etc.

By the way Philip, your reply si about what I experienced with OPC and BACnet. Not at all impressed I am afraid. Makes me want to stick to proprietary PLC netwrok drivers - they generally work much better.

 

[PhilipW]

Bob,

Overall we were quite happy with the OPC arrangement. Inititially we tried the Citect ABCLX driver, but we found that there were some severe limitations when addressing members within UDT tags....and by then my program had been written totally around them. At that point we tried the OPC client with RSLinx instead.

At the outset the Citect OPC client gave us all kinds of grief, but that was because we now had lots of screens with tag names, but not attached to valid addresses...and this was the cause of the slow response. Quite understandable really.

The advantage of using RSLinx was that we could use RSLogix5000 and Drive Explorer and route through the various networks with ease.

 

[Marie]

Thank you for your answers...

Something strange is happening to my system... If I go see the S7 connection diagnostic, my connection is "Not used". I never managed to change that. When I communicate with OPC Server (OPC SCout), my OPC connection changes to OK.

If I try to use Citect, with the S7NT server and the Application connection of Netpro, nothing works, no errors execpt the hardware error in Citect (PLC offline, cannot talk). I think the problem is in my Citect config...

Here is what I've got:

Do you see any problem???

Thanks

Marie

 

[John Gaunt]

Hi Marie,

I suggest you tick Extended Forms in Citect Editor
Tools / Options to display the lower part of the
form I/O Devices. Often it is necessary to set up
some variables here.

Otherwise I can't see a problem but I have only used
Citect OPC with some very specialised gas metering
equipment.

Regards........John Gaunt

 

[JesperMP]

Hi,

just guessing from the screenshots (hard to see though), but I dont think that the S7NT driver in Citect is an OPC connection. The reference to "S7ONLINE" seems to indicate that it uses the Simatic Net software more directly somehow.

Here is a wild stab at it:
Dont specify the I/O device Address as "S7connection_1". I guess this is a connection you have defined in NetPro. In stead simply specify the MPI address of the PLC in question.