[Elecraft] Long RS232 Runs - RS422

[Cliff Frescura]

RS-232 use +3 to +15VDC and -3 to -15VDC for signaling levels, thus -5 and +5 will work too, but *not* 0VDC and +5VDC

Like others, I've run RS-232 over 100's of feet.  RS-422 will go much further and has the advantages of multi-drop and noise immunity due to its differential nature.

73,

Cliff K3LL

-----Original Message-----
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of WILLIS COOKE via Elecraft
Sent: Thursday, January 21, 2016 11:53 AM
To: jim at audiosystemsgroup.com; elecraft at mailman.qth.net
Subject: Re: [Elecraft] Long RS232 Runs - RS422

The old criteria was 50 feet, but that was set before the specification for any twisted pair for digital, let alone Cat 5.  In short, it it works well, it is OK but 200 feet sounds reasonable.  RS-232 uses a 5 volt signal level.  RS-422 uses a higher signal level, I believe 12 volts, but that is from memory.  Watch out for the serial dongles that plug into USB ports.  Some are not full RS232 and do not work except with certain connections, ham radio applications not included.  Be careful and if it does not work, keep trying different dongles or get on the internet and find the brand and source for one that will work.  If all else fails or if you want to be sure, buy a card based RS-232 or 488 interface that uses all DB-9 or DB-25 connectors.   Willis 'Cookie' Cooke,VP of Tidelands ARS and TXPE K5EWJ & Trustee N5BPS
 

      From: Jim Brown <jim at audiosystemsgroup.com>
 To: elecraft at mailman.qth.net
 Sent: Thursday, January 21, 2016 12:44 PM
 Subject: Re: [Elecraft] Long RS232 Runs - RS422
   
On Thu,1/21/2016 10:32 AM, Michael Walker wrote:
> I wanted to mention that for those that want long RS232 runs for 
> devices (Steppir, Rotator, Elecraft Amp),

It helps to define "long." Distance for RS232 was originally defined in feet. Many years ago, it was redefined in terms of capacitance between conductors. Using cables as common as CAT5, lengths of 200 ft or more are no problem. Simply use one pair per signalling circuit.

73, Jim K9YC
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