[Coco] Supercomm woes continue...

[KnudsenMJ at aol.com]

In a message dated 8/15/04 10:12:21 AM Eastern Daylight Time, james at skwirl.ca 
writes:

> Thanks, I took a quick look at it. I think, at this point, that in 
>  order to know if things are going as they should be, I need some sort 
>  of device to plug in between the cable and the RS-232 Pak, to see which 
>  signals are high/low.

Radio Shack sells (or used to sell) a little DB-25 sex-preserving 
double-ended device with LEDs on it, that you splice into the cable for just that 
purpose.  I think I even have one here, which I last used when trying to get a serial 
printer to work on my Linux PC.  (Turned out that serial printers need a Null 
Modem cable, so lots of tinkering was involved.  Finally got the parallel 
port enabled and abandoned the whole enterprise, garbled characters and all.)
 
>  Because I wrote up my little app to drive DSR high (there's only one 
>  outgoing handshaking line on Mac serial ports, and it's labelled as 
>  CTS, and it should be high, according to the reports from the system 
>  calls on the Mac end), 

CTS should be incoming; RTS is the outgoing -- but I suspect we're just doing 
semantics here.

You probably know this, but some RS232 leads are define "High/True" when 
negative, and "False/Low" when positive, IIRC.  But ISTR the LEDs on that Radio 
Shack gadget always read green for true/high.

BTW, I just found it, and it's not from RS, but "salvaged" from my last job.  
But I do recall seeing the same thing at the Shack, so go look.

I also have a RS null modem in-line connector plug, sex-preserving.
--Mike K.