12-06-2012 10:18 AM
Hello,
I hope someone can help me to find out what is the problem using modbus tcp ethernet available from the ni library.
I have Labview 2012 installed and i'm trying to communicate with some ethernet cards through modbus tcp. Using labview modbus ethernet master and slave examples in the same computer allowed me to understand how the basic modbus communication is done in Labview, but when trying to connect to other modbus programs or even the ethernet cards, it shows the error 56 (exceeded time limit). When using a communication monitor to analyse the modbus commands, i've noticed that the MB ethernet example master always sends the same message, despite of the changes in the subVI that are done before execution. The message sent from the example is like this
000000000006000200000004
followed by another message of
Error 2 does not allow broadcast
Since i've tested every part of the example, changed it to write single register and see if the message sent was different from the original and getting always the same result, i'm starting to think that LabView 2012 has some problem using modbus tcp ethernet communication.
What can i change in modbus functions in LabView MB ethernet example master subvis to be able to send to ethernet cards modbus tcp messages like:
Write Single register (to register 68)
00000000000601060044FFFF
Thank you in advance.
12-11-2012 06:32 AM
Hi,
Maybe this explain the behaviour : http://digital.ni.com/public.nsf/allkb/12A88A47D3F863C586256FE8005478CA?OpenDocument
Best regards
Jean-Luc D. NI France
National Instruments France