DDE Topic won't terminate from VBA

[HuntWhenever 0]

I have recently installed RSLinx Single Node and I'm writing an Excel macro to read some recipe data from some PLCs.  The macro is pretty straight forward with one exception:  I can't seem to get the DDE topic to terminate so I can read a different PLC (RSLinx Single Node only allows one topic at a time).

Here's my macro in a nutshell...

Private Function OpenRSLinx(Topic As String) As Long

On Error Resume Next
    OpenRSLinx = DDEInitiate("RSLINX", Topic)
    If Err.Number <> 0 Then
        MsgBox "Error Connecting to Topic", vbExclamation
        OpenRSLinx = 0
    End If

End Function

 

Sub ReadClick()

    Dim UsedTopic As String
    UsedTopic = Cells(1, 1)
    rslinx = OpenRSLinx(UsedTopic)

    'Reading code goes here

    DDETerminate rslinx

End Sub

 

This works for one PLC.  When I change to a different PLC (different topic), I get an error because RSLinx Single Node cannot run more than one topic.  When I look at the Active DDE/OPC Topic List in RSLinx, the first topic I ran is listed as Active.  Also, when I bring up the DDE/OPC Topic Configuration menu in RSLinx, in the Topic List on the left hand side shows the topic I just ran with a lock symbol beside it.  The only way I can run another topic is to shut down RSLinx, then run my macro again with the different topic name.

 

Am I missing something here?  All the research I've done indicates that DDETerminate is all that should be needed.

 

Additional info:

 - Windows 10 Pro

 - Office Excel 365 version 2005

 - RSLinx Classic Single-Node Revision 4.12.00 CPR 9 SR 11.0

Edited 19 Jul 2020 by HuntWhenever
typo

[Izzybe 13]

@HuntWhenever, at first glance it looks everything is fine even with the ddeterminate command. Try changing the command to DDETerminateAll. 

Some rslinx packages only offer one topic (one device) or none.

• Rslinx OEM and rslinx PRO handle multiple DDE's.
• Rslinx single node is the name says - a single device , so one dde.
• rslinx lite - no dde support.

 

Sub ReadClick()

    Dim UsedTopic As String
    UsedTopic = Cells(1, 1)
    rslinx = OpenRSLinx(UsedTopic)

    'Reading code goes here

    DDETerminateAll

End Sub

Edited 19 Jul 2020 by Izzybe

[HuntWhenever 0]

16 hours ago, Izzybe said:

@HuntWhenever, at first glance it looks everything is fine even with the ddeterminate command. Try changing the command to DDETerminateAll. ...

When I try DDETerminateAll, I get a "Sub or Function not defined" compile error.

[Izzybe 13]

Interesting DDETerminate works while DDETerminateAll doesn't. Does DDEPoke or DDERequest work on your script? 

run your code in debug mode, and step through each line. Keep your online tags short maybe one in case of troubleshooting.

In your vb editor tools --> go to references. Dialog box will open and look for the missing library, the last library with a checkmark will start with missing and then its name. check the missing library and then hit ok.

Otherwise you need to call it out as an Application.DDETerminateAll

[HuntWhenever 0]

27 minutes ago, Izzybe said:

Interesting DDETerminate works while DDETerminateAll doesn't. Does DDEPoke or DDERequest work on your script? 

run your code in debug mode, and step through each line. Keep your online tags short maybe one in case of troubleshooting.

In your vb editor tools --> go to references. Dialog box will open and look for the missing library, the last library with a checkmark will start with missing and then its name. check the missing library and then hit ok.

Otherwise you need to call it out as an Application.DDETerminateAll

DDEPoke works.

I've stepped through the program a few times using a break point before and after the DDETerminate just to make sure it was executing that line.

I looked through references, but the DDE functions are part of the Excell.Application as far as I know.

I looked in the VBA object library.  DDETerminate was listed in the Excell.Application class, but DDETerminateALL was not listed (image attached).

 

[Izzybe 13]

Thanks for your reply :) I dont have the single node version. The only way would be to open and kill your actual rslinx application within your readclick() subroutine. 

Sub ReadClick()

   Dim vPID as Variant

   Dim UsedTopic As String

    

'point to your rslinx location

    vPID=shell("C:\programs\rockwell automation\rslinx.exe", vbNormalFocus) 

    UsedTopic = Cells(1, 1)
    rslinx = OpenRSLinx(UsedTopic)

    'Reading code goes here

    DDETerminate rslinx

    'your code for terminating rslinx program from your pc. 

         'dim

               '.... see below note what to insert

 

          'end if

 

 End Sub

 

 

There is a sample code on this forum on how to close notepad. Replace notepad with rslinx.exe (what is shown in your task manager as running process name)

You would copy from first dim --> to end if command  and paste it to 

http://www.vbaexpress.com/kb/getarticle.php?kb_id=811

 

keep me posted

[HuntWhenever 0]

Interesting work around.

I'll give that a try here in a few days.

Thanks!