27 Jun
2006
27 Jun
'06
8:54 a.m.
From: Jules Richardson <julesrichardsonuk at
yahoo.co.uk>
I've got some equipment here that has RS422 serial on it - i.e. it uses
differential signal pairs rather than RS232's reference against ground.
Question is, can I wire up a cable so that I can use an RS232 terminal with
this RS422 equipment? (running over a short distance)
A lot of RS422 equipment uses TTL level to create the +/- signal lines
- hooking it directly to RS232 may blow up your tranceivers, not work,
or both. Or, it may work - I think old Macs were tolerant enough to
do that.
The only "proper" way is to use a RS232 tranceiver chip (like MAX232)
and 422 tranceiver chips (such as 75176(? - it's been a while)) or a
creative arrangement of transistors and resistors.
I can send you a quick schematic if you need.
Joe.
27 Jun
27 Jun
9:09 a.m.
A lot of RS422 equipment uses TTL level to create the
+/- signal lines
- hooking it directly to RS232 may blow up your tranceivers, not work,
or both. Or, it may work - I think old Macs were tolerant enough to
do that.
Yes, Macs with RS-422 ports usually could take RS-232 (using a converter
cable) without a problem. I did this all the time.
--
--------------------------------- personal: http://www.armory.com/~spectre/ ---
Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser at floodgap.com
-- Once, adv.: Enough. -- Ambrose Bierce, "The Devil's Dictionary"
------------
9:47 a.m.
Am 27 Jun 2006 6:09 meinte Cameron Kaiser:
As far as I understand it's the other way arround, a 422 Eq is given and
a 323 Terminal is about to be connected.
H.
--
VCF Europa 8.0 am 28/29.April 2007 in Muenchen
http://www.vcfe.org/
A lot of RS422
equipment uses TTL level to create the +/- signal lines
- hooking it directly to RS232 may blow up your tranceivers, not work,
or both. Or, it may work - I think old Macs were tolerant enough to
do that.
Yes, Macs with RS-422 ports usually could take RS-232 (using a converter
cable) without a problem. I did this all the time. 
10:36 a.m.
Joachim Thiemann wrote:
That's interesting - it does look like it's possible to bias & jumper the
inputs (RXD & CTS) on this equipment so that it protects the receivers.
Unfortunately the documentation I've got for this particular board isn't high
on detail; I've got some docs on later revisions though so will check those.
From what I gather, it should be jumper-selectable to talk to RS232C, RS422,
or RS423.
cheers
Jules
From: Jules
Richardson <julesrichardsonuk at yahoo.co.uk>
I've got some equipment here that has RS422 serial on it - i.e. it uses
differential signal pairs rather than RS232's reference against ground.
Question is, can I wire up a cable so that I can use an RS232 terminal
with
this RS422 equipment? (running over a short distance)
A lot of RS422 equipment uses TTL level to create the +/- signal lines
- hooking it directly to RS232 may blow up your tranceivers, not work,
or both. Or, it may work - I think old Macs were tolerant enough to
do that. 
9:59 a.m.
Jules Richardson wrote:
That's interesting - it does look like it's
possible to bias & jumper
the inputs (RXD & CTS) on this equipment so that it protects the
receivers. Unfortunately the documentation I've got for this particular
board isn't high on detail; I've got some docs on later revisions though
so will check those. From what I gather, it should be jumper-selectable
to talk to RS232C, RS422, or RS423.
I'm not intimately familiar with the spec, but isn't RS423 very similar
to RS232?
Peace... Sridhar
6596
days inactive
6596
days old
4 comments
5 participants
participants (5)
-
Hans.Franke＠siemens.com -
joachim.thiemann＠gmail.com -
julesrichardsonuk＠yahoo.co.uk -
ploopster＠gmail.com -
spectre＠floodgap.com