FW: [ct-user] CT's -LOOP option

Cady, Fred Cady, Fred" <fcady@ee.montana.edu
Mon, 24 Feb 1997 17:36:57 -0700

Somewhere in my (and the CT) archives is a blurb I wrote up on the -loop
cabling.  If it doesn't show up soon I'll try to extract it.  I agree
with the answers that have been given below except I think it is better
to make up the loop boxes such that you DO use NULL modem cables between
computers.  That way you can use the cables in an environment that has
computers with multiple serial ports.  You also don't need to make up
boxes, cut metal, etc., if you make a Y-splitter cable with the DB-9
73, Fred, KE7X

Fred Cady
Department of  Electrical Engineering
Montana State University
Bozeman, MT  59717

> ----------
> From:
> owner-ct-user@ve7tcp.ampr.org[SMTP:owner-ct-user@ve7tcp.ampr.org] on
> behalf of ieefc@msu.oscs.montana.edu[SMTP:ieefc@msu.oscs.montana.edu]
> Sent: 	Saturday, February 22, 1997 4:51 AM
> Cc: 	ct-user@ve7tcp.ampr.org
> Subject: 	Re: [ct-user] CT's -LOOP option
> TOMK89@aol.com wrote:
> > 
> > Is there anybody around that could give me a better understanding of
> the
> > -LOOP option in CT?
> I have built 2 loop boxes for use with CT.  I will try to answer
> your questions.
> > I have these specific questions in mind:
> > 1. Does there need to be a complete loop between all stations? (i.e.
> 1 to 2,
> >    2 to 3, 3 to 1).
> Yes.  The loop must be continual, or it will not work.  You may wire
> as many positions as you need, or, wire more than you need, and use 
> jumpers, which you can make, if there are computers missing.  
> In my case, I built each box for 6 computers.
> You should use DB25 terminals.  In my case, I used females on the
> box.  The box is wired as follows:
>          DB25 #1      DB25 #2   
>           Pin 2   to   Pin 3
>           Pin 4   to   Pin 5
>           Pin 6   to   Pin 20
> Continue this pattern for each DB25 in the box.
> The loop must be continual, as I said, so the pins on  DB25 #6 (or
> whatever the last one in your box is) get wired back to DB25 #1 .  
> If you need a schematic, I can provide you with one.
> > 2. Without using a null modem cable what pins need to be connected
> from
> > station to station?
> Cables must be straight through.  No null modems in the cables.  You
> are
> effectively building the null modems into the box by wiring pin 2 
> on one computer to pin 3 on the next computer.
> After the box is built, and the computers hooked up (use DB25 to DB9
> converters to any 9 pin serial ports) you must do a few more things
> to make the box work.
> 1 - TSRs must be loaded, on all computers, with the -RTS parameter.  
> This puts the RTS/CTS signals on Pins 4 and 5.  You can load it 
> with -DTR parameter too, I guess, which puts the DTR/DSR signals
> on pins 6 and 20.  
> Actually, I am not clear about this (I am not a computer guru).
> I don't know if both types of flow control work at the same time,
> or if you only can use one or the other.  It appears that you can 
> put both parameters on the COMTSR# command line, but only one works.
> We have had success using -RTS, giving us RTS/CTS flow control.  
> I do not know if both actually work.  Maybe one of you computer types
> can tell me how this works?  I wired the boxes with both 4/5 and 6/20 
> connected.  This may be overkill, and unnecessary, because maybe you 
> can't use both types of flow control at the same time.  I really don't
> know.
> 2 - When you load CT, you must put the -LOOP command on the command
> line at each computer.  This tells CT that you are using the -LOOP.
> The usual caution that each computer must have its own number,
> and that the MULTI.CFG file must be present AND THE SAME, on
> all computers in the loop.  
> Also, we have had varying results with baud rates.  We run 
> ours at 9600 baud, but we have high speed 16550 COM ports 
> on all of the computers.  If you have computers without these
> COM Ports, you may have to set the loop to run at a lower baud rate.
> Good luck.  Let me know if I can be of further assistance.
> 73,  de Gene,  N2BIM
> n2bim@NJDXA.org  (Alias for n2bim@warwick.net)

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