Re: Two quick RS-485 questions

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View
Thanks muchly to all who replied. I am in good shape to get this
project completed. It's a fun little item. And the news that I can
maybe run as much as several thousand feet on cat5 is great, because I
still have no info on that second site.

Re: Two quick RS-485 questions
Quoted text here. Click to load it

I think a current loop might be your cheapest option. You would need a
proper 'driver' at the TX side while all receivers are merely cheap
optocouplers at a fraction of the price of an RS-422/485 receiver. And as a
bonus, you'll get galvanic isolation for free.

Quoted text here. Click to load it

With 2400 bps and a current loop you could even use fence wire. So yes, cat5
will be fine :-)

Meindert



Re: Two quick RS-485 questions
Quoted text here. Click to load it

Ah, but I'm required by the customer to use RS485, sorry. I should
have made that clearer in my original posting.

BTW, the driver/receiver I'm using is the SN75LBC179P, which is $1.26
in 25pc quantities, not too bad. I just finished a nasty prototype PCB
layout and created the BOM, and I find that as long as they make at
least 10 of these, it's going to be _way_ cheaper than my ballpark
guess. Since they already have purchase approval for the ballpark
guess, I come out looking like a hero for being under budget ;)

Re: Two quick RS-485 questions
Quoted text here. Click to load it

That is indeed cheaper than the Maxim counterpart.

Quoted text here. Click to load it

:-)

Meindert



Re: Two quick RS-485 questions

Quoted text here. Click to load it

Cheapest is probably a generic 75176, e.g.  DS75176BM or SN75176AD, ~ $0.20
each / 100.

--

John Devereux

Re: Two quick RS-485 questions

Quoted text here. Click to load it

Where do you get new ones for that price? Cheapest I have seen is double
that.

Thanks,
Joe Legris


Re: Two quick RS-485 questions
On Mon, 03 May 2004 19:05:01 -0400, the renowned Joe Legris

Quoted text here. Click to load it

Digikey has the TI ones for 0.21 in 500, should be possible to do
better.

Best regards,
Spehro Pefhany
--
"it's the network..."                          "The Journey is the reward"
snipped-for-privacy@interlog.com             Info for manufacturers: http://www.trexon.com
We've slightly trimmed the long signature. Click to see the full one.
Re: Two quick RS-485 questions
Quoted text here. Click to load it

But in qty 100 they're 38 cents each.

--
Joe Legris


Re: Two quick RS-485 questions
On Tue, 04 May 2004 08:24:41 -0400, the renowned Joe Legris

Quoted text here. Click to load it

Or maybe they are 0.21 each with a $17 line-item nuisance charge.

Best regards,
Spehro Pefhany
--
"it's the network..."                          "The Journey is the reward"
snipped-for-privacy@interlog.com             Info for manufacturers: http://www.trexon.com
We've slightly trimmed the long signature. Click to see the full one.
RS-232 question
While were talking about prices, what's the best choice (i.e. cheap) for
a MAX232 equivalent that the uses 0.1 uF caps?

Thanks,
Joe Legris


Re: RS-232 question
: While were talking about prices, what's the best choice (i.e. cheap) for
: a MAX232 equivalent that the uses 0.1 uF caps?

ST232 ? (SGS Thomson, www.st.com)

--
  ******************************************************
  Never ever underestimate the power of human stupidity.
We've slightly trimmed the long signature. Click to see the full one.
Re: RS-232 question

Quoted text here. Click to load it

Best I found was ST232CW or (TI) MAX232D for ~$0.50 for ~50
pcs. (Would be interested in others).


--

John Devereux

Re: RS-232 question
says...
Quoted text here. Click to load it
Sipex SP232ECP, last buy was ~$0.53 each.

Re: Two quick RS-485 questions

Quoted text here. Click to load it

EBV / Avnet in UK for SN75176AD / 150 pcs.
Future in Canada for DS75176BM / 95 pcs.

This was in late 2003, so I suppose prices might have changed a bit.


--

John Devereux

Re: Two quick RS-485 questions
On 04 May 2004 19:12:43 +0100, the renowned John Devereux

Quoted text here. Click to load it

FAI's web site price is about triple that.

Best regards,
Spehro Pefhany
--
"it's the network..."                          "The Journey is the reward"
snipped-for-privacy@interlog.com             Info for manufacturers: http://www.trexon.com
We've slightly trimmed the long signature. Click to see the full one.
Re: Two quick RS-485 questions

Quoted text here. Click to load it

Really? Well, this wasn't off the web site, it was a direct quote. Perhaps
there was a glut of them at that time.

--

John Devereux

Re: Two quick RS-485 questions
On 04 May 2004 22:35:52 +0100, the renowned John Devereux

Quoted text here. Click to load it

Web site prices tend to be on the high side compared to distributor
quotes in combination with other stuff (juicy total order size), at
least in my experience.

Best regards,
Spehro Pefhany
--
"it's the network..."                          "The Journey is the reward"
snipped-for-privacy@interlog.com             Info for manufacturers: http://www.trexon.com
We've slightly trimmed the long signature. Click to see the full one.
Re: Two quick RS-485 questions
Quoted text here. Click to load it

There is some reason why I chose this particular part, but I didn't
make a note of it. (I have a half-page of scratch paper with part
numbers on it, most of which are crossed out). Well, anyhoo, I'm about
$30 per unit under budget for the entire appliance, which is great
heaping bowls full of meaty gravy, and there is much rejoicing.

Re: Two quick RS-485 questions

Quoted text here. Click to load it

For some further information about RS485, check out this app note.
It describes 10 ways to "bullet proof" RS485 interfaces.

http://www.national.com/an/AN/AN-1057.pdf

Regards
David Milne


Site Timeline