Maker Pro
Maker Pro

Who-da Thunk?

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Joined
May 8, 2012
Messages
4,960
I want to preface this with a bold statement.... I have just about every configuration of RS232 cables and adapters known to man and I have them in duplicate x 10.

This morning the wife says.. "Gee, this is odd. This month you didn't buy a single China - Ebay item". That got me to thinking. Since PC RS232 ports have become as rare as Hen's teeth we all have become very comfortable with USB/RS232 converter dongles. They're fine for what they're intended for but if you're hooking up a Null Modem link it requires two USB/RS232 dongles with a F/F Null Modem (crossover) adapter connecting the two dongles. I thought why not buy a nice compact USB_Serial_Serial_USB Null Modem cable? I figured China must have packaged this by now.

Unless my search terms suck it doesn't exist. Yes, I realize that if each USB end is going to be plugged into the same PC each USB jack would have to assign a different ComPort# for each USB port.

I think my description is clear enough but if a drawing of what I'm looking for is needed I'll draw it.

Chris
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Joined
Jan 21, 2010
Messages
25,510
Tell us what you want to do, not how you think it should be done ;D
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Joined
May 8, 2012
Messages
4,960
Actually I was running a forum deciphering test. :D You all failed miserably. No CIA, MI-6 annalist jobs are waiting for you. :p

OK, I'll post a schematic or sketch later.

Chris
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Joined
May 8, 2012
Messages
4,960
Harald goes home with one gold star for understanding my question by a factor of 50%.

OK, here's my explanation. In the old days when all PC's had RS232 ports you could link two PC's with a Null Modem cable. If a single PC had two serial ports you could also communicate between the two ports using the same Null Modem. This was handy if you were testing VB MSComm code between two VB projects on the same PC. The same Null Modem would be used when communicating between a PIC simulator app that I have that includes a Virtual Serial Terminal.

Fast forward to today where finding an RS232 port on a PC is rare but they're all bristling with USB ports. To do what I described above requires a [USB to Serial} {Null Modem} {Serial to USB] as shown in the attachment and how I've been doing it for years. It's a royal Pita and I would love to have it packaged as a single USB to RS232 to USB cable.

Chris
upload_2016-11-23_8-30-58.png
 

Harald Kapp

Moderator
Moderator
Nov 17, 2011
13,700
Joined
Nov 17, 2011
Messages
13,700
I would love to have it packaged as a single USB to RS232 to USB cable
But, for goods sake Chris, why would you need the detour with the RS232 in between? Is it because you wnat to use a virtual COM port for communication? The I think this is what you're looking for: two USB plugs connected by a cable. Each plug has its internal FTDI chip which emulates a virtual COM port (VPC).
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Joined
May 8, 2012
Messages
4,960
Yes to all of your questions Harald. That's exactly what I'm looking for. Thanks!! That cable is unique because it can be used in Virtual CommPort (VCP) mode or direct USB-2 to USB-2. Depending on the drivers used for the null modem link. They supply both and can be selected and changed to use in either mode. Cool!
http://www.ftdichip.com/Support/Doc...I_Drivers_Installation_Guide_for_Windows7.pdf

DUNKA!
Chris
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Joined
May 8, 2012
Messages
4,960
You know the old saying "You gain something. You loose something"? Well it just hit me that using that USB Null Modem cable I loose the use of my inline RS232 LED testers that I've been using for well over a decade, maybe two.

http://www.ebay.com/itm/RS-232-DB25...321466?hash=item2cb0f3b07a:g:7LcAAOSwQ15XOZ8l

I find it humorous that after all these years they still haven't corrected the typo "DRT" that should read "DTR".

http://www.ebay.com/itm/Startech-MT...828794?hash=item33bd36f9ba:g:Qq4AAOSw2GlXEBzq


Oh well, you can't win em all.

Chris
 
Top