RE abt seraial communication

[kevalvakani]

hello all

i m a student from INDIA


i want to do data exchenge between two serial ports using PLC SOFTWARE(SIMULATOR) by using com port RS-232 in that one com port is of PC in which software of any plc is installed and in the other comm port is of an embeeded pc


shall i able to do this

or else if you can give me idea based on that case



plz reply fast as i have only few days left for deciding the project

waiting for reply

 

[danw]

Communications is more complicated than connecting a properly wired cable between two ports.

The dreaded OSI model shows the various layers needed in communications:

Not all layers are needed for all applications, but I know of no application that succeeds with only the lowest red frame, the physical link, which is what RS-232 ports are.

This example from Novell shows what goes on in each layer for a networked message transfer (colors don't match and the layers are inverted):

The point being, while you might have sufficient access on the side with the software to point to a port and let the software handle some comm, it isn't clear if you have access to the embedded device to effect or realize successful communications.

The fact that two devices each have a serial RS-232 port does not mean that the port is accessible or that there is an upper layer application that handle and interpret the data.

Making it all come together could certainly be a project, but do you get credit for a project in which the end result is failure, but you learned a lesson?

 

[kevalvakani]

tanks for your reply
plz tell me is it possible in case of ethernet ports?

 

[danw]

No, ethernet ports are just another form of serial ports. They're just ports.

The key to data communication is not ports, the key is sofware/firmware.

You want to do "data exchange". Doing so requires software/firmware that can monitor a port, handle the data, and do something useful with it.

What software/firmware is now or can be put on both ends (PC and embedded device) that is client/server or master/slave or whatever protocol that can monitor the port you designate and handle both incoming and outgoin data and perform the appropriate "data exchange" task with it?

How will you access the embedded device to install software/firmware to accomplish this?

The software/firmware determines which ports it can use.

You're starting at the wrong end of data communications. You need to figure out the software/firmware end first.

 

[kevalvakani]

abt serial communication

dear sir
sorry for troubling you as i m new in this

but i just want to know that is it possible to send data to my com port using any PLC SOFTWARE(SIMULATOR) without using any hardware
is it available?
thanks sir for your keen interest

 

[danw]

I can't answer your question. I'm not familiar with PLC Software (simulator). I just know about digital communications in general.