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How to interface RS-485 / Modbus protocol

How to interface RS-485 / Modbus protocol

How to interface RS-485 / Modbus protocol

(OP)
I 'd like to interface the Recorder (Screen Master2000:ABB) with a host computer. The recorder use RS-485 and modbus protocol for interfacing. Can anyone suggest me ,how to interface (Hardware and software)?. Is it require to use adaptor from RS-232(serial port at host computer) to RS-485?  and the software which developed for RS-232, can it  be used for this applicatiion?
                                   Thanks for your kind
                                     PAP

RE: How to interface RS-485 / Modbus protocol

Use rs232-rs485 converter.
Write programe to communicate with the device.
Read data from the device.
if required i can send small programme to read data from the device.
After reading data you have to decode.
The address details of the device is required.

c b ramesh
Director
Interface Electronics pvt ltd
19 nana street
t nagar
chennai
India
email:ife@vsnl.com

RE: How to interface RS-485 / Modbus protocol

Software part:
if converter supports full duplex mode
you can write you program as usual RS232
communications, else you have to control
RTS/CTS signals.

For testing purposes I use COM PORT TOOLKIT
software available at http://golikov.newmail.ru/eng/index.html

RE: How to interface RS-485 / Modbus protocol

Pap;
Seems to me that the easiest part of your problem is the hardware interface - writing a Modbus protocol driver from scratch will be a tedious business. I've done this for the Omron Host Link and Allen-Bradley DF1 protocols and i recommend finding a pre-written (and debugged) library if at all possible. If you are determined to write the code yourself, this site has the description:
http://www.modicon.com/techpubs/toc7.html

Good luck...

RE: How to interface RS-485 / Modbus protocol

you can find that information in the following address:

www.modbus.org

I hope that this thing can help you.Let me to know if this is right.

Fernando Sánchez

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