I use a Prolific adapter made by Startech.

The other choice is an ExpressCard like this one:
1 Port ExpressCard Serial Adapter Card | ExpressCard Serial Adapters | StarTech.com

It contains a hardware UART which will always work, with everything.

thanks for the info Aaron.

So far I have tried:
Sabrent USB 2.0 to Serial (9 pin)
$14.99
Office Depot
(didnt work )

GIGAWARE® USB TO SERIAL CABLE
Details Gigaware USB to Serial Cable : Cables, filters & adapters | RadioShack.com
$24.99
(would connect, but comes up with "ON Comm error #" even when comm's are set

so I think I'll try the Prolific for sure.

same error
 

i know this is an old thread but i have a lt10 with a serial usb dongle and i cant connect keeps on saying on comm error # how did you solve it
note i previously had a 9pin dongle with and adapter and that worked fine.
i tried all different drivers, diff os, correct settings but keeps on giving me the "ON comm error #"

bump?

i use FTDI chipset adapter and have good luck with them.

ok problem is if you install the drivers from microtech efi on windows 10 it does not work.

you need to plug it in then say get drivers from windows update, then it works.

this is for windows 10 with the USB dongel not the RS232

Windows 11
 

Mines doing same thing. Just brought new cable and dongle but won't connect brings up the gauges but just times out or refreshes back to connect screen please help so fustraing

Hello,

Ive spend up to now a few hours trying to get a ltx-12s to talk to the software. it doesnt. Ive did the things from post #4 to all the com ports I tried. I tired a laptop with win10 with a native com port; Ive tried a laptop with win7 with 3 differente ftdi based com to USB and ive tried an old normal computer with a native com port running windows XP.

always I have the same outcome wich is that the software seems to connect; although the display on the top left keeps saying "connecting please wait" and displays gages but no data is coming in and it does also not show any maps if I click on it. when I power down the ecu or unplug the serial cable it notices it and goes back to the home screen in the disconnected mode.

I also have an old MT-12 which does the same but I think this ecu is not even meant to be tuned used a laptop? Is there anything else worth trying before I throw them ecus in the bin?

what I maybe can also mention is that when plugged in the ecu lits the green led and red red one blinks slowly like 3 second or so period. I have the ecu on the bench and just connected the ground, battery and 12v ignition to a 12v supply. when powering on one hears a relay click in the ecu