Modbus libraries for LabView 8.0

[Christian_nor]

Hi,

Yes, this is working

I am using the LV 7.0 libraries provided by unclebump. (I have only tried serial communication, not tcp/ip)

-Christian

[Khalid]

Dear UncleBump,

Do you mind sharing the TCP version of your Modbus VIs?

Thank you,

-Khalid

[Khalid]

Manfred (and others),

Have you been able to use the TCP Modbus Slave example to write out any values succesfully?  I am able to read values into my Slave VI example, but I can't seem to be able to write values out. 

Thank you,

-Khalid

[unclebump]

Here is a link to a modbus ethernet query llb file. I've never used the ethernet slave vi's.

http://forums.ni.com/ni/board/message?board.id=170&message.id=144522&query.id=35841#M144522

[unclebump]

Modbus slave devices can only receive data. It takes a master device to write data.

[Khalid]

Thank you UncleBump.  What I meant by slave writing was, when I change the values within the Slave (Coils and Registers), these do not get picked up by the Master.  This should be doable. 

In any case, thank you.

-Khalid

[Christian_nor]

Another question. I am supposed to write data to address 429 and 430. Something is not right, I am trying to write 14 to 429 and 5 to 430, 14 is correct read and the module replies. But the module is not sending any datas to 430(at least that is what the module says). See attatched figure for my configuration. Anyone?

[unclebump]

There are different modbus function codes for writing single registers and multiple registers at one time. Try changing the six to the appropriate number for write multiple registers.

[unclebump]

Here is a link to the modbus function codes manual.

http://www.eecs.umich.edu/~modbus/documents/PI_MBUS_300.pdf

[Christian_nor]

Thanks, but this did not work. I changed to function code 16, which is supposed to be preset Multiple registers. See attatched configuration. Now none of the datas were accepted.