Modbus Serial Simulator

Hi All,
Am new to labview, I want to create modbus slave simulator. I have connected through serial port to the master and treid to read the holding registers, the VI is executed succesfully but it doesnot show the expected register values read. Can you guide me with any of the examples to create Modbus Slave simulator.
Thanks in advance.
SS

Hi All,
Thanks for your response, Yes I did use some of the VI's from Modbus Library : MB Serial Example Slave VI and MB Serial Example Master VI, but upon modifying registers in slave its not updating on Master. PFA VI's am using. I have cross connected the two ports but still its not updating. Please advice
Thanks,
Savi
Attachments:
Slave.png ‏65 KB
MasterVI.png ‏64 KB

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Dear all,
I have a job to write a labview program to communicate with a TEC controller..
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Thank you!!

You asked many of the same questions and got answers in this thread.
I don't understand why you are asking them again and I don't know why
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If
your laptop/pc has a serial connection, then you do not need anything
more than the correct cable to connect to an RS-232 connection on the
instrument. If the instrument requires RS-485, then you need a
converter. If your laptop/pc does not have a serial port connection,
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and obviously, you would want the correct type (either RS232 or RS485).
You keep talking about RS232/RS485 as if they are the same thing. They
are similar but not identical. You have to know which one the
instrument has.
If you don't have NI-VISA on your laptop, it's because you did not install it.
I also don't understand the previous answer about tulip support. It is not at all relevant and not at all necessary for support of a USB-RS232 converter.

Eurotherm 2704 connection via serial port with ModBus

Hello guys,
first some words about my problem:
I have to develop a software which allows reading and writing the
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I wrote already the program and it works, but I used "iTools OPC
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http://forums.ni.com/ni/board/message?board.id=170&thread.id=468139&view=by_date_ascending&page=2
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Modbus Command ?!!!
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Hello Putnam and Christian,
I think the problem because you can not understand my question is my English, sorry
I'll try it again:
@Christian:
Thank you for the links, but I think all threads in NI Forum with topic "Help, Eurotherm 2704 ?" were written by me
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@Putnam:
In the meantime I found out, why I got an error with “my modbus serial query.vi” (the solution was very simple, I had to close the OPC-Server ).
It runs now and I try to understand now how the VI exactly works.
Maybe you can help me with it?
I try to explain what I understood, if something is wrong, tell my please:
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And if I need the value of Loop2 (the address is 01025), I have to set the start address for example to 1000 and in this case the 25-th element in register-array is the value for PV Loop 2 ?!
I got this idea, after I left the laboratory and could not try it out. I can do it first at Monday, but I would know if it is correct what I think.
If it is correct, I think I will able to change “my modbus serial query.vi” on my own, that it works in my program.
Or there is a better example/solution than “my modbus serial query.vi” ?!
The other problem would be writing of temperature, but I will ask about it later . First temperature READING problem!!
Thank you!
Alexander.
Message Edited by alexphysiker on 01-29-2010 05:30 PM

How to implement Modbus Ethernet communication in Lookout, if we want to simulate the PC as PLC ?

Problem Description :
Dear Sir,
We are doing a project where we are using Lookout with
Front end Modicon PLC. The communication is by
Ethernet, using Modbus.
Since the installation is at a distant place, we wanted
to use another PC (running Lookout) to simulate the
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Modbus object as Master
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details of what we have done, at the end of this email)
We also tried connecting the above 2 PC's as
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If instead of PC (b) we connect the Modbus simulator to
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communication between 2 PC's using Modbus serial,
and Modbus Ethernet. A detailed step by step procedure
would help us a lot.
Thanking you
Warm Regards
Raja Mahbubani
Procedure of our trial with ethernet.
This is what we have done in detail.
On PC A:
We created an object (Pot) and connected it to
the modbus data member of the modbus object say 40001. In the
properties of the modbus object we selected modbus ethernet mode
of communication and in the IP address field we wrote the IP
address of the machine B to which we are trying to communicate
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Trial 1 : We created a modbus slave object and
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Trial 2 : We created a modbus object on machine B and we wrote
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NI Software : Lookout
Version : 4.0.1 or 4.5
OS : Windows 98
NI Hardware : N/A
Drivers : N/A
Other Hardware/Instruments : N/A
CPU : Pentium
RAM : 64
Vendor : S-Tech
Customer Information :
Raja Mahbubani
Theta Controls
IN
[email protected]
Ph: (+91) 20 4222556/7

The ModbusSlave which comes with Lookout currently supports only Serial communication. So, you cannot use Ethernet between your two PCs. At least not with Modbus Master-Slave setup (if you must speak Ethernet between the two PCs, IPASCII object lets you do that, but then you'll need to implement your own protocol).
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Modbus I/O Server at Run-time

Hello everyone.
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There are some screenshots that I took while running the software at the both (develop. and client) machines above.
Regards,
Leandro Rondon
- Sensoft Indústria e Automação Ltda.
- Work phone: +55 16 3413-5489
- Cell phone: +55 16 8827-4025
- [email protected]

Forgot the images:
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2) running the installed software at development machine
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Attachments:
007Dh.png ‏17 KB

Hello Frank,
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Message Edited by Ravens Fan on 10-06-2008 08:55 PM
Attachments:
MB RW Hld Reg CTA.vi ‏46 KB

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Solved!
Go to Solution.

Simple solution once I dug into the MODBUS Serial protocol/TCP protocol documentation available out there via Google.
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