[ct-user] CT's -LOOP option

Gene Ingraham, N2BIM Gene Ingraham, N2BIM" <n2bim@njdxa.org
Sat, 22 Feb 1997 03:51:08 -0800

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

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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