Modbus Ethernet Slave coils and discrete inputs

[jorgelopes]

Hi,

I'm having serious problems in the comunication of more than 16 bits for coils or discrete inputs.

In this forum i've read some few post about this matter, tried the possible solution but got nothing working.

Guess that there is some kind of limitation or error in the ModBus modules available at the NI Labview webpages.

The idea is very simple:

I want to be able to sent 32 bits of coils from the ModBus Ethernet Master to the slave and sent 64 bits of discret inputs from the ModBus Ethernet Slave to the Master.

Can someone please give me a push? Im' kind of newbie with the Labview and would apreciate if someone that had this problem resolved could guit me a hint.

My best regards, Jorge

[jorgelopes]

I've found a solution for the problem.

Here's the link:

http://forums.ni.com/ni/board/message?board.id=170&message.id=260075&jump=true

[jorgelopes]

The problem remains in the discrete inputs case.

I can't read more than 32 discrete inputs from the Modbus Ethernet Slave.

Is there an error stil in another part of NI_Modbus.vi ?

Perhaps in another .vi library?

[Florent_A]

Hi Jorgelopes,

thank's for posting  on National Instruments forum.

Can you tell me if you want to communicate with an automate or a computer.

If you do not tried between two computer I suggestion to make the test.

Can you send the VI with which you encounter this trouble?

Best regards,

[jorgelopes · Accepted solution]

I've already solved the problem. After all, the issue was the same and all I needed to do was to restart the Modbus Slave in one of the PC's.

Thanks for the time anyway.

I have just one sugestion for the NI folks. Once the bug is known by the comunity and was solve, why not make available a "clean" version of the ModBus.vi for download?

It would avoid many post about this same issue and help other developers.

My best regards, Jorge Lopes