I think we see that the adapter manufacturers use different chips and change them at will. I saw Kevin's posting and bought one of the Sabrent adapters actually marked as FTDI. It works fine. I can't explain what I see but maybe this post will save a little heartache and prevent those returns to Amazon. I've updated my original post to add the Sabrent CB-FTDI adapter and I include the update here :
WIU to TIU Connection
I did a test of which cables/adapters would work between the WIU and the TIU. The WIU was loaded with v1.1 software and the TIU was loaded with v6.10 software. I did this test in March of 2024 when I purchased the adapters listed - I assume this means that they are current production.
I've had a WIU for 5+ years and an IOGear GUC232A USB to RS232 adapter which is working fine between my WIU and TIU.
I recently bought another WIU so I ordered another IOGear GUC232A adapter. It did not work - the purple TIU light on the WIU never came on.
As I've read on several posts, its likely that the IOGear adapter, over the years, has been redesigned - now using a different chipset which is not supported by the old Operating System inside of the WIU.
So I went on Amazon, eBay and DigiKey and bought several adapters to test.
Here are the results ("works" means the purple TIU led came on and I could control engines via the WIU - "does not work" means the purple TIU led did not come on.):
Manufacturer Model # Chipset Result of Test
------------ ------- ------- --------------
Sabrent** CB-DB9P PL2303 does not work
Sabrent CB-FTDI FTDI works
Oikwan FT232RL FTDI works
Startech ICUSB232V2 PL2303 does not work
IOGear GUC232R PL2303 does not work
Pololu 391 CP2102 does not work
TrippLite U209-000-R PL2303RA does not work
Conective Peripherals UC232R*** FTDI works
UGREEN**** ?? PL2303 not tested
TRENDNET**** TU-S9 PL2303 not tested
** The Sabrent CB-DB9P is the adapter recommended in the WIU documentation and indeed may have worked at some point in the past. The system log file as pointed out by H1000 shows that the Prolific PL2303 chipset should work but I they didn't work for me.
*** email from <info@mthpartsandsales.com> said to use FTDI UC232R - Digikey number ES-U-1001. This is not a cable type adapter but a 3 inch long plastic box with a USB connector on one end and a DB-9 on the other. Connects nicely between the WIU and TIU. It looks like there are some variants of this adapter that are actual cables.
**** Once I saw that adapters with the Prolific PL2303 chipset did not work, I canceled my open orders for these adapters.
