MODBUS protocol implementation

[ssddii]

hey !
need help!!
i need help
i want to automate an equipment that support MODBUS RTU framing.So the commands written in the manual are so what like

IA FUNC    count           values        CRC
01 02         02                    00 20                 FA2B


everything is in hex .
so should i convert it to ascii before sending everything????

[unclebump]

You could try the NI modbus library.

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

[andre.buurman@carya]

Hello,

You should keep the information to be send in hex format.

Google for the modbus RTU specification, the document give great insite in the modbus protocol, so it will be easier to spot a problem.

Modbus RTU framing requires timing to detect end of message.

http://www.modbus.org/specs.php

Its always a good plan to get specifications when you can.

Kind regards,

André Buurman

[unclebump]

Also download portmon so you can see what is being sent out the port.

http://www.microsoft.com/technet/sysinternals/utilities/portmon.mspx

[ssddii]

hey uncle bump !!!
need your help urgently
i found a vi named  MB modified3.vi for modbus reffered by you on a forum, but it has several subvi missing like MBdcimal convert,Mbcrc.vi,MBwaitforserialregisters.vi,MBwaitforserialDigstatus.vi
can you provide me with the whole package.
it would be good for me.
thanks and looking forward
sdi