Is Enron Modbus supported?

[Dave Rathnow]

Hi there,

I'm new to the world of Modbus and just discovered libmodbus.  I like what I've seen (and tried) but I'm wondering if libmodbus will work the the Enron Extensions?

Thanks,

Dave.

[Chuck Watson]

Based on this link, I would say yes. It looks like there is nothing special about Enron Modbus.

 

http://control.com/thread/1026233164

 

You would have to handle addressing yourself in your code to make sure that you don’t use an address the incorrect way for 32-bit values.

 

Chuck Watson BS, CEM, CMVP

Direct USA 724-799-1529

--
Vous recevez ce message, car vous êtes abonné au groupe Google Groupes "libmodbus".
Pour vous désabonner de ce groupe et ne plus recevoir d'e-mails le concernant, envoyez un e-mail à l'adresse libmodbus+...@googlegroups.com.
Pour obtenir davantage d'options, consultez la page https://groups.google.com/d/optout.

[Dave Rathnow]

Thanks Chuck.  That seems to indicate it will support the Enron extensions, I'm just not sure what will be delivered back when I make a read request.  That is, how libmodbus will handle 32bit register values.  I'll have to try it out and see.

[Dave Rathnow]

I may have spoken too soon...

If I'm dealing with 16 bit numbers, there is no problem, but things fall apart when I try to deal with 32 bit values.  After trying this out, I found that modbus_write_register function call will only send a 16 bit number in the modbus command.  The modbus function codes are the same but the function call will only put 16 bits of my 32 bit value into the request.

On Thursday, September 22, 2016 at 1:38:19 PM UTC-6, Chuck Watson wrote:

[Chuck Watson]

Have you tried modbus_write_register. It uses a different function code than modbus_write_register.

 

http://libmodbus.org/docs/v3.0.6/modbus_write_registers.html

 

Chuck Watson