hi,

we are in need to implement modbus RTU/ASCII on our server to get data from PLC. Please let us know the hardware and software requirements from both the ends.

 

Get the Modbus specification:

http://www.eecs.umich.edu/~modbus/documents/PI_MBUS_300.pdf

You can get an inplementation at:

http://pvbrowser.org

Documentation->rlllib->rllib reference manual

 

Hi,

You need to have a MODBUS Master RTU/ASCII on your server inorder to communicate with the MODBUS Slave PLCs. Either you have to get the souce code libraries of MODBUS Master and implement the drivers that could be used by yor application in the server or you have to get MODBUS Master DLL's or ActiveX components whose exported functions could be called to communicate with the MODBUS Slaves.

For more info mail me or check website http://www.sunlux-india.com.

Cheers,
Santhosh
[email protected]

 

Hi

You can download vb modbus project at http://www.modbus.pl

Regards
Andrzej

 

Dear Mr. Amol A Kurdukar,

With the information you've provided, i can give the requirement chart as shown below:

S/W:
----
A modbus master driver runs on your server.

H/W:
----
You must be knowing that the PC has RS 232 communication port. So your PLC need to have either RS 232 port or RS 485 (with RS 485 to RS 232 Converter).

I need the PLC details & information about the application to give you the right solution. Feel free to contact me for more details.

Nishad Roshan. P
[email protected]
--------------------------------------------------

 

The MatPLC project (http://mat.sf.net) has a modbus master module. The other requirements depend on what you intend to do with the data afterwards...

On the slave end, it depends on the PLC: either it supports Modbus, or it doesn't. The manual or your dealer should be able to advise.

Jiri
--
Jiri Baum <[email protected]> http://www.csse.monash.edu.au/~jirib
MAT LinuxPLC project --- http://mat.sf.net --- Machine Automation Tools

 

Generally you need a RS232/485 port. The software requirements are really dependant on what you want to do with the data. If you have an existing SCADA package then it is almost certain that there will be a modbus driver supplied with it or available. Any of the solutions mentioned above will require a bit of programming expertise in either C or Visual Basic to interface to the DLL's and make them usuable to an application. Let us know what your application is and we can possibly advise on a solution.

Andy
[email protected]

 

You need a communication driver on your server side to communicate with your PLC. The best one I found is from Sapia. They have a variety depending on your driver needs. I have used their stuff and it's good. Their website is http://www.sapia-inc.com. Once you have the driver in place, then you just need to know what registers in your PLC have the data you want.

Good Luck.

Michael Stevens