custom network driver

[henryk]

I am looking for some advice...

I need to be able to write a custom network driver. The network is similar to x3.28

There seems to be very little out there so I cannot even take a driver for x3.28 and modify it. It looks like I need to start from scratch.

I am looking for a tutorial, referance example, and an approach to this problem.

Anything similar would be great!

henry

[David_Pratt]

Hey Henry,

I'm having difficulty finding low-level information about the x3.28 protocol.  If you could provide any information about its baud, parity, data bits, stop bits, etc... I could possibly help you out more.

Also, I found some developed drivers for some specific instruments here.  Perhaps you can use these as a guide for developing your own.

Thanks,

[henryk]

Thanks for the reply David

I have a detailed spec for our version of it which is unfortunately  proprietary

The protocol impliments three of the standard seven layers. The hardware layer is usually serial (RS232, 485 )

I have never written a network driver like this and was looking for some general advice for implimenting a stack based driver.

The link you provided seems to provide a x3.28 interface to gpib. Unfortuntely I need to provide the extra bits our protocol containns and on serial.

I have learned that x3.28 is also called data highway, but have not found any examples to use as a starting point. 

There are a whole bunch of serial message based protocols out there, but no referance material on how to create them

henry

[Albert.Geven]

Hi Henry

Is this driver using 8bits serial than it can be implemented on top of visa.

All you need to do is the real protocol on top of that. splitting and combining bytes and sending acknowledges.

[David_Pratt]

Hey Henry,

In addition to Albert's post, NI-VISA can handle any serial protocol that uses data bits of 5, 6, 7, or 8.  And stop bits of 1.0, 1.5, or 2.0.  If your version of x3.28 doesn't utilize any set of those parameters, our driver won't work for your implementation.

As Albert also said, protocol itself should be simple formatting of the bytes you'll be sending over the serial layer so as long as you understand the formatting and functions to generate that format, a simple state machine architecture should help you easily build a flexible, polymorphic driver for your system.

Thanks,

[henryk]

Thanks for the info.

Visa is defintely capable of delivering the coms from a hardware perspective.

The protocol is however more of server client based setup than most message based "connections"

In that sense and because multiple slaves are supported I had thought that perhaps a mechanism that plugs into the project  I/O Server section might be more appropriate.

Is there any referance material availble for creating a new I/OServer type? in case you are curious I found a good description of x3.28 from ABB see attached.

[Sammy Z]

Dear henryk,

Could you please clarify what you mean by the protocol being more like client server based.  Also what devices are slaves here? 

What type of information are expecting to send and receive that you don't think VISA can?

Thanks,

Sammy Z.