Using Labview to read a modbus

[Bart Jackson]

The other packages still all come down to normal serial port
communication, but they are helping you out with things like CRC checks,
binary formats for sending values and things like that. If you have
decent documentation for your instrument, and the modbus protocol, you
should be fine writing your own software. The commercial packages can
help you out with modbus protocol if you don't want to do it yourself,
don't have the time yourself, ... whatever.

I don't know busview, so I have on opinion as to its utility.
Bart

[urs boegli]

Denise,

I would like to recommend to use a ModBus PCI card instead of the
converter. Modbus is half-duplex (both data directions, but one after
the other one) and RS232 is full duplex, needs one more wire and so both
data flow directions are allowed at the same time.
Using Converters you have to to switch between send and receive
typically with the RTS signal availible on the RS232 plug. You have to
wait some time for the answer and you need to find some delay times for
the switch between send and receive.
Using a PC card (ie Moxa Industio) you have not to care about this
switching timing problems - you can just send and receive data as it
would be full duplex, all the problems are handled by the card and it's
buffers.

Good luck
Urs Bogli

Ben schrieb:


> Hi Denise,
>
> RS-232 to RS-422 converters are cheap and readily available.
>
> By one of these, plug it in, use the existing drivers.
>
> Problems? maybe wiring the gizmo if you do not have documentation on
> pin-outs.
>
> Ben

[km76107]

Hi Denise

I would really appreciate if you can forward me those German and Norwegian sites that have the LabView modbus VIs. I am trying to read data from a modbus device using LabView.

Thanks in advance.

[nag123]

hi all i am new mod bus library my question is  i want read data my  trip unit which is already configred in modbus register mapping  .i want read that information and decode into individual bits?my qusetion is what ever the data come outside is word or boolean. the data word is decimal or hexdecimal formate?

[Tushar_Jambhekar]

actually you should not waste your time in writing modbus protocol... NI Has already done it for You and the code is completely open without password protection.

You can find it here

http://sine.ni.com/devzone/cda/epd/p/id/4756

i have written some wrapper functions for the library which simoplifies its use... if you need i can give make it available free of cost

[darksidePrinceton]

I managed to implement the Modbus VIs with the 9871 serial port module, but still communication to my device is not working. Is there any reference as to how one uses Modbus to communicate to devices?

[RavensFan]

Go to www.modbus.org.

[muks]

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darksidePrinceton wrote:
I managed to implement the Modbus VIs with the 9871 serial port module, but still communication to my device is not working. Is there any reference as to how one uses Modbus to communicate to devices?

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Started at 2002 and getting a reply in 2004,07 and 10. Please start a new thread and explain breifly the "not working part"