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[ts-7000] Re: Using DIO to implements a current loop transmiter

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Subject: [ts-7000] Re: Using DIO to implements a current loop transmiter
From: "enrique_cesena" <>
Date: Thu, 08 Oct 2009 02:04:28 -0000
Thanks for all charlie, I'll been searching for some samples or try to use the 
already Serials in the board with any combination of interfacing and tell you 
about the progress.

Regards 

Enrique

--- In  "Charles" <> wrote:
>
> 
> Hi Enrique -
> 
> --- In  "enrique_cesena" <enrique_cesena@> wrote:
> > 
> > Thanks A lot Charlie
> > 
> > --- In  "Charles" <charliem_1216@> wrote:
> > >
> > > 
> > > Hi Enrique --
> > >
> > > It seems to me that RS-232 to current loop converter hardware would be 
> > > the best approach.  Why do you think it would not work?  To do serial 
> > > communications (either RS-232 or current loop) with bit-banging DIO, you 
> > > must essentially re-invent the whole UART & tty stack from scratch.
> > 
> > I'm for sure that any converter would be ok, but there's some reasons to 
> > try implement the comm "as part" of board, it is possible to connect up to 
> > 16 devices, so any solution would be expensive and not able to implement 
> > with a minimum system like TS. In other hand i thought possibly there's 
> > some samples to implement the use of DIO from scratch. Of course always be 
> > there the option of use converter (this option is that I currently use) 
> > perhaps I have to start telling you that, In the past I was using a 
> > combination of a Server with SO installed, with an external RS232 - current 
> > loop converter.
> > 
> 
> Do you have any control over the devices, or only your server?  If you do 
> have some control, you could make the 16 devices passive and the server 
> active (supplying power), arrange them in a daisy-chain and use a single 
> current loop UART.  But then you have to have a communication protocol 
> designed so the client devices don't try to speak simultaneously.  I guess 
> that's why the HART protocol came about (digital communication on top of a 
> current loop backbone).  But HART is overkill here.
> 
> > Concluding the most important thing here is to reduce space, electronics, 
> > and costs.
> 
> Well, good luck; sounds extremely unlikely to me to do 16 current loop serial 
> comms by bitbanging GPIO.  Remember your time is valuable too (right?)
> 
> regards, .......... Charlie
> 
> > 
> > Thank you again for all your answers
> > 
> > Regards
> > 
> > Enrique
> > 
> > > > 
> > > > I'm trying to implement if not with DIO alone (sounds impossible to me) 
> > > > but with the minimal implementation of electronics. The question it can 
> > > > be: Is there any diagram or anybody knows how to implement a current 
> > > > loop serial communication using directly the TS DIO? it's ok if is 
> > > > necessary to use an external implementation of electronics 
> > > > (opto-isolator, amplifiers, resistors) including external power for the 
> > > > isolated side. 
> > > 
> > > I've used B&B Electronics for conversion stuff in the past, and I see 
> > > they have an app note about current loop communication:
> > > http://www.bb-elec.com/bb-elec/literature/tech/curentlp.pdf
> > > 
> > > regards, ........ Charlie
> > > 
> > > > 
> > > > Kind of Regards
> > > > 
> > > > Enrique
> > > > 
> > > > > 
> > > > > regards, ......... Charlie
> > > > > 
> > > > > > 
> > > > > > Thanks in Advance
> > > > > > 
> > > > > > Enrique
> > > > > >
> > > > >
> > > >
> > >
> >
>




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