We developed a testing device using Wago Modbus/TCP device 750-342. For communication with the device we use wago MBT.dll. So far, the work was done only WinXP and worked like a charm. Now we want wo migrate to Win7. But there we have the problem that we can access the device for about 3-4 cycles, but then the connection stops to work, without any error from the dll.

Now, can you suggest us an alternative and how do we have to approach this?

Many thanks!
Michael

 

I´m experiencing the same problem reading from module Wago 750 unit using MBT.dll on Windows 7. The device returns data for a couple of cycles (arbitrary in our case), but then it mysteriously starts returning 0-values. The funny thing is that it worked fine just two days ago.

We don't think its a socket problem, looks more like something has happened to the dll.

Did you ever find a solution to your problem? If so, any hint would be greatly appreciated.

Regards
Magnus Lundberg

> We developed a testing device using Wago Modbus/TCP device 750-342. For communication with the device we use
> wago MBT.dll. So far, the work was done only WinXP and worked like a charm. Now we want wo migrate to Win7. But there we
> have the problem that we can access the device for about 3-4 cycles, but then the connection stops to work, without
> any error from the dll.

> Now, can you suggest us an alternative and how do we have to approach this?

 

I developed a 'Home Control' (PLC-style) application (C++) about 8 years ago based on the 750-342. I wrote my own TCP libs for that purpose because everything I stumbled across was simply pure crap. My lib has a very clean interface, the source is easy to read (always my main goal) and understand. That software runs for almost eight years now on a Win2000 installation with the only break downs in case of a power loss. No leaking, nothing. A few month ago I was playing with the two spare 750-342's I own, this time under W7/64. Since them I'm banging my head against the wall because it has the same problem you describe. On W2K I have about 170cycles/sec, on W7 it runs for about 5sec and then it stops for another 5sec and so on. The funny thing is, EVERY other lib, including every Java implementation I came across has the exact same problem. I have 20+ years experience in developing professional software (mainly C/C++) but this problem seams to be the first one I can't solve ...

 

Try looking first to the behavior of the timeouts and retries parameters of your communication driver.

Another cause may be the firewall settings. Try to deactivate all security settings and or antivirus programs.

 

I am also experiencing this problem. code that has and is running under XP still works fine. same code running under Windows 7 exhibits random delays. all other services turned off. Wireshark sees the issues but does not indicate the cause.

 

I resolved this issue by running the following command.
netsh interface tcp set global autotuninglevel=disabled

reference
http://support.microsoft.com/kb/947239

has to do with devices that do not adhere to MS TCP optimizations on Windows 7.

 

That worked for me! Thanks for sharing!