I am new to SCADA systems. Recently i was going through some modbus tcp related documents.

My quess is If I write a C++ application that makes a PC behave as a modbus TCP slave, then How can i write data to memory/registers so that a modbus TCP master can read that?

 

Check out automatedsolutions.com for a Modbus/TCP Server (Slave) ActiveX Control that handles all the Modbus stuff for you and provides a simple API for read/write access to Modbus registers.

http://automatedsolutions.com/products/modbusslave.asp

-Mark
http://automatedsolutions.com

 

Hello,

It depends on the way How you are going to use/develop the scada system.

I make my SCADA applications using .NET platform & use the communication drivers from www.Parijat.com
Those drivers are based on .NET technology, so no extra software installation needed.

I am using their MODBUS TCP/IP both Slave as well Master drivers from many years.

They are also providing Demo application, so you can test your Master application with their PC resident Modbus TCP/IP Slave driver.

Thanks,
Dixit

 

Hello,

If you have already got your code to manage the client/master connections, then all you need is to create arrays with in your program.
For 0x: Bool array
For 1x: Bool array
For 3x: Int array
For 4x: Int array
The limits of the array will be the memory map you want to manage within this 'server'
I have an up & running Modbus-TCP server coded in VB. Mail me if you need further help.

 

If your goal is to learn Modbus, this is fine and can work.

If your goal is just testing your SCADA, then you will find many free (or nearly-free) Modbus/TCP slave 'simulators' online. Just search for "modbus slave simulator" and you'll find them.

Also, if you plan to do any TCP programming, make sure you have wireshark (free/open-source at source-force) oe some other tool which can decode Modbus/TCP over the wire.