troubles with the modbus protocol

[scorpio]

Hello there,   I have a trouble here with the Modbus protocol; I have already read the forums and saw that there are some issues with modbus tcp;  I have the latest  DSC 8.0 module and also Labview 8.0;  I think that maybe this issues have been fixed.

There is a demo of Modbus in the examples and it work fine on my computer and and also on two different computer; But if I want to create my own simple application to see if it works , it doesn't work;  

Attached you can see a zip file with the two projects;  Please someone check it for me  and let me know what the problems are;  If I have this simple app. working then I will move on to my  really application.

Thanks,

scorpio

[nickf]

scorpio,

  Make sure you have defined an IP address in the Modbus IO server.  When I opened your project I noticed that one wasn't defined.  You can use 127.0.0.1 to point to the local computer. 

Regards,
Nick F.
LabVIEW DSC R&D

[scorpio]

Dear Nick,

The master I/O server in my project is pointing to my  local host 127.0.0.1;  For the modbus slave you cannot configure the IP address; 

A collegue is also trying to find the problem.  Attached you can see a word document he made illustrating the problem.

Thanks,

scorpio

[nickf]

scorpio,

  All the steps you outlined in the attached document look valid.  One suspicion I have is that the ModbusSimulator example library may still be deployed.  Because of how Modbus TCP works you can only have one Modbus slave on any given IP address.  Since your master VI shows green arrows when you run that means it's connected to something.  --Another quick test would be to open the ModbusSimulator example again and set some values on that front panel.  You'll probably notice that the indicators on your master VI change.

  Use the Variable Manager (Tools>>Shared Variable>>Variable Manager) to remove the ModbusSimulator and ModbusDemo libraries, then run your VIs again.

Regards,
Nick F.
LabVIEW DSC R&D

[scorpio]

Nick,   that is indeed the problem;   Many thanks,

scorpio