Connecting to OPC Server

Hi,
I'm a newbie to DSC module and i have a question on OPC connectivity. With the base Labview (non-DSC) you can connect to OPC servers through Datasockets, although I understand that Datasockets is not a true OPC client and there are some limitations. With the DSC module, however, LV is a true OPC client. How do I connect to OPC servers in DSC module? Is the only way through the tag engine? Do datasocket vi's in non-DSC work the same in DSC?
Thanks!

Yes and Yes. In DSC, you connect to OPC Servers via the Engine (and there are tools to browse the OPC Servers and create Tags for them, set your client's settings, etc.)
And DataSockets work exactly the same in DSC.
Khalid

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Problem to connect with OPC Server opc.sinumerik.machineswitch using DS_Open

Hi,
I want to connect to an Siemens OPC server type opc.sinumerik.machineswitch using DS_Open calls (CVI 6.0) to read few tags. Running my client software (as well as the NI- sample test client) locally on the same computer as the server the connection works and I can access the tags.
Running the client-software on a remote PC then the DS_Open call "hangs-up" (not even an error message). All the DCOM settings etc should be ok, since I can access the tags using the Siemens Client OPC-Scout as test client.
I have used the same calls in several previous applications and it works with other servers (Bachmann, WinCC), so I am pretty sure that I use the correct URLS etc.
What can be the reason for a specific incompatibility?
Any idea is highly appreciated.
Cheers,
Ronald

Hi Roland,
as experience shows, Remote DataSocket is hard to implement.
The best way to implement this communication is the following:
First of all, check the DCOM -Settings
Using OPC via DCOM with Windows XP
http://www.opcfoundation.org/DownloadFile.aspx?RI=326
Use the “NI-OPC Server” to create a tunnel between the Siemens OPC server and your PC.
Install the NI-OPC Server on your PC and use the “OPC DA Client Driver” to access the tags on the Siemens OPC server.
After that you can access the created tags in the NI-OPC Server with CVI and DataSocket.
Please download the NI OPC Servers Evaluation-Version to test communication.
NI OPC Servers
http://sine.ni.com/nips/cds/view/p/lang/en/nid/209059
Download NI OPC Servers Evaluation
https://lumen.ni.com/nicif/us/evalopc/content.xhtml
Regards
Ulrich

Problem with connecting remote OPC Server

Today, when I opened my labveiw 8 program which worked properly yesterday, it couldn't connect to the Items on remote OPC server anymore thought I can still browse those items in Server Explorer. In the NI published variable monitor, quality for those items is "Server failure", Then I added a new variable which bind to a local OPC item, it works properly. What's the difference between labview8 and Server Explorer when they are used to view a OPC Item?
LabVIEW 8.20程序设计从入门到精通已经出版，敬请关注！
欢迎访问LabVIEW学习乐园: http://labviewstudy.blog.edu.cn

I've solved the problem, the reason is that the NI variable engine log on as the system account, I changed it to the specified user which I used it in DCOM config, then it's ok
the method is: computer management->Services->NI variable Engine->log on->this user...
LabVIEW 8.20程序设计从入门到精通已经出版，敬请关注！
欢迎访问LabVIEW学习乐园: http://labviewstudy.blog.edu.cn

How to understand the Error message of the connection of OPC server

hi guys, one issue need your help
when I run the NI OPC servers, one error message will appear in the process information.
Just like as followed:
===========================================================================
2011-6-23   11:50:05   Default User   NI OPC Servers   Stopping Simulator device driver.
2011-6-23   11:50:05   Default User   NI OPC Servers   Closing project D:\National Instruments\Shared\NI OPC Servers\projects\simdemo.opf
2011-6-23   11:50:25   Default User   NI OPC Servers   NI OPC Servers
2011-6-23   11:50:25   Default User   NI OPC Servers   Unable to load driver DLL 'D:\National Instruments\Shared\NI OPC Servers\drivers\dataforth_isolynx_u.dll'
more messages
=============================================================================
how to understand "2011-6-23   11:50:25   Default User   NI OPC Servers   Unable to load driver DLL 'D:\National Instruments\Shared\NI OPC Servers\drivers\dataforth_isolynx_u.dll'??????
Thanks

Hi!
I have the same problem when opening the OPC Server.
Unfortunately I have no solution, but I think it has something to do with incorrect Certificates and is more of a Windows Problem.
If anybody can help, please let us know!
Best Regards
Martin

OPC SERVER/CLIENT

Dear Sir
I try to connect the opc server.And I have connected the server successed.But there is question confused me as below:
code as below that for additems after connected the OPC server
If WriteItemIndex > 0 Then
            WtInputItemColl.AddItems(WriteItemIndex, WriteItem, ClientHandles1, ServerHandlesWtIn, ErrorsWtIn)
            WtInputGrp.IsSubscribed = True
End If
Running code, vb2013 show the message:"
An unhandled exception of type 'System.Runtime.InteropServices.SafeArrayTypeMismatchException' occurred in OPC_CLIENT1.exe
Additional information:The specified array was not of the expected type.
I checked the AddItems.Syntax
AddItems (Count As Long, ItemIDs() As String, ClientHandles() As Long, ByRef
ServerHandles() As Long, ByRef Errors() As Long, Optional RequestedDataTypes As Variant,
Optional AccessPaths As Variant)
I can not find the error,I have defined all the variants as syntax
    Dim ServerHandlesWtIn(100) As VariantType
    Dim ServerHandlesRdOut(100) As VariantType
    Dim WithEvents WtInputGrp As OPCGroup
    Dim WithEvents RdOutputGrp As OPCGroup
    Dim WtInputItemColl As OPCItems
    Dim RdOutputItemColl As OPCItems
    Dim ClientHandles1(100) As Long
    Dim ReadItem(100) As String
    Dim ReadValue(100) As VariantType
    Dim WriteItem(100) As String
    Dim WriteValue(100) As VariantType
    Dim ErrorsWtIn(100) As VariantType
    Dim ErrorsRdOut(100) As VariantType
    Dim WriteItemIndex As Long
    Dim ReadItemIndex As Long
Please help me find it,thank you!

Hello Yu Du,
This looks like VB6 code. This forum is only for VB.Net since 2002. VB6 is not supported anymore. Have a look at this page and post to the linked forum:
Visual Basic 6.0 Resource Center
Armin

OPC Server login

Good afternoon ...
I am using labview 2010 and NI OPC Server. I wanted to know first how to put a username and password in NI OPC Server and then as I move to the labview user and password to connect the OPC Server.

If you mean NI OPC Server, it is a trial.
If you mean can Lookout act as an OPC server, it is full.
Forshock - Consult.Develop.Solve.

OPC Server S7 1200 cannot pass data to VI

Hi,
I use siemens s7 1200 plc with labview 2011 and Opc server 2012. I can connect to opc server and create tags. Moreover, I am able to see data changes with quick client.
The problem when I try to create I/O server and bound with shared variable, I pass it to VI. All tags are zero, I believe there is no communication to servers. Although there is no error message. Any suggestions?
Please see the posts
Attachments:
Vi.JPG ‏43 KB
server.JPG ‏37 KB

Hello sir,
We are too handling a project and stuck with the same problem. The OPC quick client shows the updated value but while using the opc variable in the labview it doesn't shows any changes , So please help as with some good solution.
AEI_JR wrote:
I'm late to the party, but if you need to troubleshoot OPC communications, you should start with opening the OPC Quick Client. Check there to see if you have good connectivity - if it is broken there, you will never receive data to LabVIEW.

Help Needed in establishing connection between Kepware OPC server and UDS 4

Hi All,
I am in the process of establishing connection between Kepware OPC server and UDS 4.0,
Can anyone guide me through the process of configuring UDS 4.0 to establish conection with the Kepware.
Any standard documentation on UDS 4.0 will be of great help.
Thanks in advance,
Shyam

HI Rajesh,
I am creating OPC DA instance and when i try to browse for the OPC servers available in the machine, the list is blank. i am not able to view any OPC servers.
Actuallt the Kepware OPC server and UDS are installed in the same machine.
Can you plz through some ligh on this
Regards,
SHyam

Connecting a plc without opc server

hi, can i connect a plc to labview 7.1 (to send and read data) without an opc server, using just an rs232 cable from plc to pc.
Solved!
Go to Solution.

syd_b,
RS232 is just the physical interface, but it says nothing about the communication protocol. Allen Bradley PLCs use several serial protocols, e. g. the DF-1 protocol. You can either try to implement the protocol by yourself by using VISA calls (good documentation is required) or you can purchase a library. NI doesn't offer an Allen-Bradley library for LabVIEW, but I have found a vendor with a quick Google search.
Jochen

Is it possible to connect labview with opc server without using NI dsc Module ?

Hellow sir,
I want to get data over labview using OPC server and i am not using any dsc module vi (Alams, print, GUI, security).I am using share variable to get data from OPC server to labview. Now i want to deploy that application to third party computer. (where there is no NI software is installed)
i am using labview 8.6 and 2009.
Many ? like....
1) what is the procedure to install that application in third party computer.
2) Do i need to use my dsc run time licence..?
waiting for your valuable feed back.
Thank you.
CLAD
Labiew programmer

Hi, When you connect to NI OPC Server by creating New I/O Server > OPC Client. You will see all registered OPC Servers running on local machine or remote machine. I used KepServerEx from Kepware and LSIS OPC Server from LG with no problems. Just make sure that the OPC server is running.
Hope it helps
Waleed El-Badry MSc.,MCPD, ISTQB Certified Tester
Assistant Lecturer
Mechatronics Department
Faculty of Engineering
Misr University for Science & Technology
Attachments:
LG.png ‏57 KB

What is the best way to detect loss of OPC Server connection when using DSC Tags?

I'm using the DSC Module on a new project and I'm pretty impressed so far. The HMI Wizard has saved me quite a bit of time.
My application is configured where the DSC Tags are connected to remote OPC Server Tags.
The issue I'm having is that I cannot detect a loss of the OPC Server when the application is running. Read's of the front panel controls/indicators still return values and the little "connection" icon next them is still green. Even if the connection icon turned red it wouldn't help since the Front Panel is not visible when the main application is running. It is a Sub-VI that's in charge of OPC Data Interfacing. The rest of the application uses the data from the OPC Sub-
VI.
I cannot effect a change on the OPC Servers, so I need a method of detection when the Server is lost on my end.
Any ideas on the best way to do this?
Thanks,
Jim

Hi Jim,
Ideally, error-reporting and -handling should be the way to handle this. However, if errors are not reported/handled as is sometimes the case with OPC, a quick-n-dirty way to do this would be to check for a "heartbeat" signal from your OPC Server. This could be a boolean tag which toggles On and Off (or a counter ticking). You then read this Tag in DSC in a slow loop using the Read Tag VI (not the front-panel control). And keep track of the Changed? output from this Read Tag VI.
As long as the 'Changed?' output is true, you are receieving data from the OPC Server, and hence it's alive. You may add some deadband logic to wait for a specific period of time before declaring the Server's really dead!
Hope this helps,
K
halid

Problem Connecting Shared Variable to OPC Server

Hi All,
I use LBW 8.2.1 and DSC.
I try to connect to an OPC server : Emerson DeltaV
When using Datasocket, I am able to connect to the DeltaV OPC server and browse (DSTP Server) to the variables I want to Read/Write.
But, since I'll need to connect to hundreds of variables I want to use DSC and so the Shared Variables.
When I try to bind the variable, Labview cannot detect the DeltaV OPC Server... Browsing results in a "Populating Node" comment... But never completes...
Does anyone have a clue?
Thanx to All
Dai
Dai
LV 7.1 - WIN XP - RT - FP

Hi,
I do not trust datasocket for this. I already tried with LBW 7.1and after something like 150 datasocket connections to DeltaV OPC, some variables do not respond anymore.
It's kinda wierd. It happens to groups off variables. Just add one more connection and a all bunch off the other connections freeze. Remove it and it comes back...
One application Engineer of NI told me at the NiDays that datasocket was not meant for so many variables and that I had to use DSC.
He said something like : "Now you know why datasocket ships with Labview and that you have to pay for DSC..."
I'll take some screenshots to explain, but later... In fact, we are going to upgrade our DeltaV to version 8 or 9 soon (currently 7.4).
Dai
Dai
LV 7.1 - WIN XP - RT - FP

Can't connect to KepWare Enterprise OPC server

I am trying to connect to the Kepware Enterprise OPC server with Server Explorer 2.4.1 but get a message 'The system cannot find the file specified' 0x80070002. I have modified the DCOM setting for XP SP2 as described in the Kepware documentation. Is there a way to resolve this issue?
Thanks
Harry

Hello,
Can you explain exactly how you are attempting to connect to this OPC Server and also any of it's properties that are set in Server Explorer. At what point do you get this message? Have you been able to connect to that OPC Server on that machine, or any machine before?
Cheers
Tom | NIUK

Connect yudian controller through OPC server in Labview.

I am trying to bind Indicator using DSTP server that gets data from Yudian controller AI706M.
I want to get this data through yudian OPC server.
when I do this in labview 7.1 version with windows XP OS, I get option of yudian OPC server from browse menu available at Indicator's property and It works
but with Labview 2012 and window 7 I am not getting this option ??
I would appreciate your help on this.
Thank You
CLAD
Passionate for LabVIEW

Hi there,
According to the following link, you might not be able to connect your PLC to LabVIEW:
http://www.ni.com/white-paper/6417/en
In general, if you would like to establish a connection between LabVIEW and a PLC, here is a step-by-step guide:
http://www.ni.com/white-paper/7450/en
Regards,
Norbert

Problems connecting to a remote OPC server in write mode using CWDataSocket control

Hi.
I have been struggling with an odd feature when trying to connect to a remote OPC server using CWDataSocket control, though I'm not sure if it's a CWDataSocket related problem. But anyway, the following error occurs: "Active: Can't write data." Error number: "-2147467259". Now, when I connect to a local OPC server
and write some data and then again connect to the remote server, no errors occure and reading and writing work fine. The same error occurs when I try the same in LabVIEW. What could be the problem?
No errors occure when I connect to the server with some other OPC client application.
Thanks in advance.
- Asko -

The ConnectTo operation (as are all DataSocket operations) is asynchronous. In order for it to complete, you must process Windows messages after calling it and before calling another operation. Is it possible that you are trying to write data before the connection operation is complete?
One easy way to test this would be to put the ConnectTo and the Write in separate control callbacks, cause ConnectTo to be called, wait a while, then cause the Write to be called. Alternatively, you could do something like the following:
dsWrite.ConnectTo txtUrl.Text, cwdsWrite
While Not ((dsWrite.Status = cwdsConnectionActive) Or (dsWrite.Status = cwdsConnectionIdle))
DoEvents
Wend
If this is the problem, then you'll probably want to go with the
second option. In a production system, you should include a timeout in the While loop so that if the connection actually cannot be made, you are not stuck in an infinite loop.

Connecting to OPC Server

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