On Wed, 14 Nov 2012, Erik Christiansen wrote:
Date: Wed, 14 Nov 2012 22:03:45 +1100
From: Erik Christiansen <[email protected]>
Reply-To: [email protected]
To: [email protected]
Subject: Re: [Emc-users] Differential signal from encoders
On 13.11.12 22:37, Jon Elson wrote:
Viesturs L??cis wrote:
> I was thinking that I could try making a 422-to-ttl converter, based
> on the scheme in top-left corner of this sheet:
> http://www.kmitl.ac.th/~kswichit/Rs422/Rs422.pdf
>
That drawing uses some very old parts, and may no longer be obtainable. I've
been using AM26C32 receivers in several boards and they work well and are
good up to encoder frequencies. You should have a 100 - 120 Ohm terminating
resistor at the receive end, between the + and - signal lines.
Yes, and those old parts are annoyingly current hungry. Even the
DS26LS32A draws 50 to 70 mA. Jon's AM26C32 is better - 10 to 15 mA, and
it's good to +/- 14v input. (The RS485 permitted common mode is only 7v,
so that should be ample, I figure.) Then there's the MAX3095EPE, which
consumes only 2.4 to 3.5 mA. It's also good for +/- 25v input, and 15 kv
ESD, according to the datasheet.
Around hot machinery, I wouldn't use a commercial chip (0?? to -70??C),
only industrial (-40?? to 85??C) or better.
I'm about to order a few MAX3095EPE for the current project, but have
milled out the front panel tonight, instead of finishing the parts list
for the electronics. Digi-Key has them, in DIP16 and SOIC16 and several
temperature grades.
Erik
Our (15 year) experience with PC/104 serial cards leads us to use the 26LS32A
as they are simply more rugged than the newer CMOS replacements. We do us
Maxim parts for 3.3V and cases where low power is important.
--
Emc-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/emc-users
Peter Wallace
Mesa Electronics
------------------------------------------------------------------------------
Monitor your physical, virtual and cloud infrastructure from a single
web console. Get in-depth insight into apps, servers, databases, vmware,
SAP, cloud infrastructure, etc. Download 30-day Free Trial.
Pricing starts from $795 for 25 servers or applications!
http://p.sf.net/sfu/zoho_dev2dev_nov
_______________________________________________
Emc-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/emc-users
