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Can someone recommend A Serial to USB connector for the TIU To WIU Connection? I purchased the Sabrent USB 2.0 to Serial Adapter and it wont work. Then i bought the Insignia USB to RS -232 and its not working either. I know my WIU and TIU work as I brought it down to Sommerfeilds trains to add the new Revision and it worked on their Layout Using their Cable. He doesn't remember where he got his adapter cable. Thanks

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As Joe said! DCS box needs power, either via fix 1 or aux. Grab a cheap HO DC transformer and plug it in to AUX, or a good wallwart. Do this even when you run your trains since you will have no power to CONTROL anything if you lose power to the TIU. As many say, "This and much more can be found in Barry's book."

@cngw posted:

As Joe said! DCS box needs power, either via fix 1 or aux. Grab a cheap HO DC transformer and plug it in to AUX, or a good wallwart. Do this even when you run your trains since you will have no power to CONTROL anything if you lose power to the TIU. As many say, "This and much more can be found in Barry's book."

Thank you, I was powering it with a Z1000, then my z4000. Just cant get it to communicate with a New in Box WIU on the MTH Network

@MarkSteven posted:

Thank you, I was powering it with a Z1000, then my z4000. Just cant get it to communicate with a New in Box WIU on the MTH Network

New in box or old stock new in box? pretty much all of the WIUs shipped with old firmware installed and need to be updated to version 1.1. To check which firmware you have go to the LuCi login page and check the firmware version:

WIU Firmware check

The picture above depicts a WIU with the latest version 1.1 firmware installed.

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To be fair, here are the reasons why you were asking for a specific cable.

#1 While many different brands and chipsets of USB to serial conversion exist- they require a software "driver" on the USB logic host side of the cable. By that, I mean the WIU is a small Linux operating system "computer" for the purpose of this discussion. That operating system has to know and be able to use the specific USB to serial chipset in the cable.  So while you could plug in a cable electrically- that still means some cables- there is a chance with counterfeit or just unsupported brands of chips DO NOT WORK. So yes, 2 cables can look near identical, but have inside buried where you cannot see the chips- different brands and models of chips that will not work with the WIU.

#2 The serial side of the interface is just as much a problem. This is because there is a voltage standard for the serial interface (what voltage indicates a 1 bit and what voltage indicates a 0 bit. Given that the cable is powered from the USB side- we only have 5V DC as the source. Depending on how cheap (minimal electronics) the cable and it's USB to serial conversion is- you might only get 5V or even less out of the pins of the serial cable. Higher end and more complicated converters may have a power supply that takes that 5V from the USB and raises it to a higher regulated voltage, and then the serial data coming out of the serial data pins are at this higher voltage "standard". This PDF by Texas Instruments documents that "standard". https://www.ti.com/lit/an/slla...Fwww.google.com%252F

"Valid RS-232 signals are either in the range of +3 V to +15 V or the range −3 V to −15 V with respect to the
common ground. To be more specific, the driver output is Logic 0 when the voltage is between +5 V
and +15 V and is Logic 1 when the voltage is between -5 V to -15 V.


Received signal voltage level is that Logic 0 works on the received signal voltages up to +3 V to +15 V and Logic
1 works with voltages up to -3 V to -15 V."

Point being, the "better" (more compatible and higher voltage serial data output) cables cost more, typically have a larger electronics package and thus a box or large area where the PCB is molded into the cable to support this voltage increase (boost) and translation, compared to a simple 5V converter that is "within the spec" but at the low end of the range.

#3 As stated, the TIU is another microprocessor controlled electronic device and needs power so it can communicate. While MTH allows the TIU to "borrow" power from Fixed 1 input, ideally we want the TIU powered all the time so the WIU can communicate regardless of channel status. Thus the suggestions of powering the TIU via aux power input jack with a 12-19V supply- AC or DC is valid 1 to 2A capacity.

#4 Last- all the above has to work so the TIU processor and firmware can handshake over the serial data connection back to the WIU. So the firmware version on the TIU, the firmware version of the WIU, the USB to serial cable chipset used, the electrical interface of the serial converter and it's voltage translation has to be compatible and working with the TIU serial interface.

Any step or point anywhere along this complicated path just 1 thing is incompatible- and the TIU and WIU do not work together.

It's entirely possible a cheap cable exists and works. Further I'm not saying for sure you must have a higher voltage serial data connection and that the lower end of the range does not work, however, if having problems- this is one possible answer.

Brand names like Tripp-Lite and Saberent are good known and hopefully higher quality cables that might cost more, but are more likely to work than a given generic no name brand cable.

Sadly, there are no guarantees- with the world today, supply chain problems, counterfeit chip problems, even a name brand cable could be a problem. I know that everyone here is trying to give you best advice and what works for them.

@H1000 posted:

New in box or old stock new in box? pretty much all of the WIUs shipped with old firmware installed and need to be updated to version 1.1. To check which firmware you have go to the LuCi login page and check the firmware version:

WIU Firmware check

The picture above depicts a WIU with the latest version 1.1 firmware installed.

I brought the WIU and TIU down to The Train store Saturday.They loaded Revision 6.0 into the TIU. I cant do it because I dont have Windows Platform. We hooked everything up to their Layout and Got it all to work. Brought it all home, got a new Serial USB adapter and it wont connect. I have the MTH-1039 on pre-order since January of 2021. if its ever released and ships, I hope I dont have the Same issues. I'm running Trains with my explorer but would like more features than what it provides

To be fair, here are the reasons why you were asking for a specific cable.

#1 While many different brands and chipsets of USB to serial conversion exist- they require a software "driver" on the USB logic host side of the cable. By that, I mean the WIU is a small Linux operating system "computer" for the purpose of this discussion. That operating system has to know and be able to use the specific USB to serial chipset in the cable.  So while you could plug in a cable electrically- that still means some cables- there is a chance with counterfeit or just unsupported brands of chips DO NOT WORK. So yes, 2 cables can look near identical, but have inside buried where you cannot see the chips- different brands and models of chips that will not work with the WIU.

#2 The serial side of the interface is just as much a problem. This is because there is a voltage standard for the serial interface (what voltage indicates a 1 bit and what voltage indicates a 0 bit. Given that the cable is powered from the USB side- we only have 5V DC as the source. Depending on how cheap (minimal electronics) the cable and it's USB to serial conversion is- you might only get 5V or even less out of the pins of the serial cable. Higher end and more complicated converters may have a power supply that takes that 5V from the USB and raises it to a higher regulated voltage, and then the serial data coming out of the serial data pins are at this higher voltage "standard". This PDF by Texas Instruments documents that "standard". https://www.ti.com/lit/an/slla...Fwww.google.com%252F

"Valid RS-232 signals are either in the range of +3 V to +15 V or the range −3 V to −15 V with respect to the
common ground. To be more specific, the driver output is Logic 0 when the voltage is between +5 V
and +15 V and is Logic 1 when the voltage is between -5 V to -15 V.


Received signal voltage level is that Logic 0 works on the received signal voltages up to +3 V to +15 V and Logic
1 works with voltages up to -3 V to -15 V."

Point being, the "better" (more compatible and higher voltage serial data output) cables cost more, typically have a larger electronics package and thus a box or large area where the PCB is molded into the cable to support this voltage increase (boost) and translation, compared to a simple 5V converter that is "within the spec" but at the low end of the range.

#3 As stated, the TIU is another microprocessor controlled electronic device and needs power so it can communicate. While MTH allows the TIU to "borrow" power from Fixed 1 input, ideally we want the TIU powered all the time so the WIU can communicate regardless of channel status. Thus the suggestions of powering the TIU via aux power input jack with a 12-19V supply- AC or DC is valid 1 to 2A capacity.

#4 Last- all the above has to work so the TIU processor and firmware can handshake over the serial data connection back to the WIU. So the firmware version on the TIU, the firmware version of the WIU, the USB to serial cable chipset used, the electrical interface of the serial converter and it's voltage translation has to be compatible and working with the TIU serial interface.

Any step or point anywhere along this complicated path just 1 thing is incompatible- and the TIU and WIU do not work together.

It's entirely possible a cheap cable exists and works. Further I'm not saying for sure you must have a higher voltage serial data connection and that the lower end of the range does not work, however, if having problems- this is one possible answer.

Brand names like Tripp-Lite and Saberent are good known and hopefully higher quality cables that might cost more, but are more likely to work than a given generic no name brand cable.

Sadly, there are no guarantees- with the world today, supply chain problems, counterfeit chip problems, even a name brand cable could be a problem. I know that everyone here is trying to give you best advice and what works for them.

So basically even though I am applying power to the TIU from a Brick or Z4000, I should also apply power to the Aux. Power Input?

@MarkSteven posted:

So basically even though I am applying power to the TIU from a Brick or Z4000, I should also apply power to the Aux. Power Input?

Yes. The TIU is a piece of electronics. You cannot "guarantee" at all times fixed 1 input has power to feed the TIU logic itself. Powering via external power supply into aux in ensures the TIU logic is powered.

Well then your WIU should be up to date. the older WIU 1.0 firmware won't work with TIU firmware 6.0 & 6.1. Relating just a bit to what Vernon said above, the WIU works exclusively with Serial adapters that use the "FTDI" or compatible chipset which encompasses about 90% of the USB to Serial adapters out there. I do know of some adapters that don't work with the WIU for this reason (a couple of Belkin models come to mind).

On an unimportant side note, the WIU loads drivers for other USB based things it doesn't ever need, for example a Delorme EarthMate GPS receiver!? I guess it wants know where on Earth it is when it's running trains?

Yes. The TIU is a piece of electronics. You cannot "guarantee" at all times fixed 1 input has power to feed the TIU logic itself. Powering via external power supply into aux in ensures the TIU logic is powered.

💯% AGREED!!!  The old way of powering a TIU via the FIXED 1 INPUT should have been done away with a long time ago, I supposed 20 years ago it was a way to sell it without its own wall plug and save a little on original sale price but boy has that caused problems, confusion and many questions here on the forum.

@H1000 posted:

💯% AGREED!!!  The old way of powering a TIU via the FIXED 1 INPUT should have been done away with a long time ago, I supposed 20 years ago it was a way to sell it without its own wall plug and save a little on original sale price but boy has that caused problems, confusion and many questions here on the forum.

Partly my fault. I built a Nice 24 X 15 Foot layout, but I'm Not 'Tech Savvy" and Didnt really Study DCS enough.

Yes. The TIU is a piece of electronics. You cannot "guarantee" at all times fixed 1 input has power to feed the TIU logic itself. Powering via external power supply into aux in ensures the TIU logic is powered.

Even way back when and I was running the DCS, I put some kind of DC/aux tranformer power output into the aux pwr input on the TIU! That way, I know the TIU had power. There were too many instances of power failing/breaker tripping when supplying the TIU! Can you say "runaway train!"

We can't say for sure that putting the power into the aux will solve your problem, but before you put ANY other cables to the TIU, you should hook up the aux pwr, and see if the red light is on inside the box! That way, input to the Var or Fixed of any channel will not have to supply it. (only the fixed 1 does that anyway.)

If aux pwr (enough anyway) lights the red light, then after all other hook ups fail....you know it is NOT the power hook up anyway. Just my opinion.

@cngw posted:

Even way back when and I was running the DCS, I put some kind of DC/aux tranformer power output into the aux pwr input on the TIU! That way, I know the TIU had power. There were too many instances of power failing/breaker tripping when supplying the TIU! Can you say "runaway train!"

We can't say for sure that putting the power into the aux will solve your problem, but before you put ANY other cables to the TIU, you should hook up the aux pwr, and see if the red light is on inside the box! That way, input to the Var or Fixed of any channel will not have to supply it. (only the fixed 1 does that anyway.)

If aux pwr (enough anyway) lights the red light, then after all other hook ups fail....you know it is NOT the power hook up anyway. Just my opinion.

Thank you as well as everyone else that Replied. I did try that, Aux Power with a Brick, then with the Z4000. Just never got the TIU Light on the WIU to come on, thats with switching my Serial adapter cables. just not sure why it connected once when we tried it at Sommerfields Trains. I had full connections. Maybe it was a Fluke.

@MarkSteven posted:

Thank you as well as everyone else that Replied. I did try that, Aux Power with a Brick, then with the Z4000. Just never got the TIU Light on the WIU to come on, thats with switching my Serial adapter cables. just not sure why it connected once when we tried it at Sommerfields Trains. I had full connections. Maybe it was a Fluke.

man, this is tough. Now I read that your WIU's TIU light was never on?

So for me, this was a bad time. I blame myself for not getting every single fact right at the start. For anyone else following along, it probably will look stupid. For the OP, it was a huge waste of time.

So for the future, my advice, get all the facts right away. No light, what is exactly not working, etc., etc..

I always think back a few years to a post where the guy stated he had train, train no work. Getting anything out of him was like pulling teeth. I was wrong about my diagnosis then, and others advised that I stay away. Skip ahead to now, and I forgot that advice, and again, I am wrong here.

So for me, this was a bad time. I blame myself for not getting every single fact right at the start. For anyone else following along, it probably will look stupid. For the OP, it was a huge waste of time.

So for the future, my advice, get all the facts right away. No light, what is exactly not working, etc., etc..

I always think back a few years to a post where the guy stated he had train, train no work. Getting anything out of him was like pulling teeth. I was wrong about my diagnosis then, and others advised that I stay away. Skip ahead to now, and I forgot that advice, and again, I am wrong here.

No real need to stay away! As for, "I was wrong about my diagnosis then" just think, if for every 5 wrongs you have, you help out another rail runner with a "right"......you done good.

Life is like that. Stick in here, you have been here for years, you know this by now. And we are all better for having you here.

So for me, this was a bad time. I blame myself for not getting every single fact right at the start. For anyone else following along, it probably will look stupid. For the OP, it was a huge waste of time.

So for the future, my advice, get all the facts right away. No light, what is exactly not working, etc., etc..

I always think back a few years to a post where the guy stated he had train, train no work. Getting anything out of him was like pulling teeth. I was wrong about my diagnosis then, and others advised that I stay away. Skip ahead to now, and I forgot that advice, and again, I am wrong here.

I definitely appreciated yours and others advice. I probably didn’t describe the problem very well. To clarify… no matter how I hooked up the TIU, I always got the Power indicator light on. But only once, the TIU connection lamp on the WIU only came on once.

I just purchased two Sabrent CB-DB9P USB to RS-232 adapters to connect my WIU to my TIU. Both purchased on 16 March 2024 from Amazon. Advertised on Amazon as

"SABRENT USB 2.0 to Serial (9 Pin) DB 9 RS 232 Converter Cable, Prolific Chipset, HEXNUTS, [Windows 11/10/8.1/8/7/VISTA/XP, Mac OS X 10.6 and Above] 2."
Neither of these worked between my WIU and TIU. The pink "TIU" LED on the WIU never comes on. The blue LED inside of the Sabrent CB-DB9P comes on solid - not sure if it is supposed to or not.
I have one adapter, the "IOGEAR  GUC232A " which works fine between the WIU and TIU. I've ordered two more of these from Amazon.
Has anyone recent experience with this Sabrent adapter? Could Sabrent have changed the design so the adapters won't work any more? Could they be malfunctioning knock-offs?
Could Sabrent have changed the design so the adapters won't work any more? Could they be malfunctioning knock-offs?

Absolutely they likely changed the design. The key here is the WIU is a tiny Linux based limited operating system that ONLY has drivers and knows how to enumerate certain USB to serial adapter ICs. If the manufacturer changes even slightly (the USB to serial chip or adapter revision), the WIU has no way of knowing how to enumerate that virtual serial port.

Again, key here, while the function would at first glance appear to be agnostic, simple conversion of one type to another, there is much more going on in the background.

Again, the WIU is a very small limited operating system. The WIU function is a firmware that runs on top of this operating system. As an example, OpenWRT, an open source router firmware application can also run on top of LUCI

"LUCI (Library for User-Centered Interfaces)"

MTH used an off the shelf wireless module that is BOTH the hardware, and the underlying operating system functional software, and then the WIU is like an application running on top- routing application packets down the virtual USB to serial port interface. It was made for the specific FTDI chip used in the revision L TIU, and then likely a handful of USB to serial adapter cables and chips. The problem is- a point in time. Chips made after the core WIU and LUCI firmware was created then are not known to the WIU and not able to enumerate.

Last edited by Vernon Barry

3:11 PM 3/27/2024

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.

I've had a WIU for 5+ years and an IOGear GUC232A USB to RS232 adapter which was 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


Manufacturer            Model #                   Chipset     Result of Test
------------            -------                   -------     --------------
Sabrent**               CB-DB9P                   FTDI        does not work 
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 is the one recommended in the WIU documentation and indeed may have worked at some point in the past.

*** 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.

**** Once I saw that adapters with the Prolific PL2303 chipset did not work, I canceled my orders for these adapters.
    
I hope Amazon does not blacklist me for returning all those adapters.

Mark, Goto the system log in the LuCi interface. The WIU supports several USB to Serial devices beyond the FTDI chip:

A PL2303 based USB to Serial adapter should work. I always assumed the Tripp-Lite cable was an FTDI device because we were told that the WIU only works with FTDI based cables.

For Reference, when connecting directly to REV. L TIU, the system log indicates connection via an FTDI device:

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Last edited by H1000

*** 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.

Great info Mark, but I do have one quibble.

The UC232R-10 at Digikey sure does look like a traditional USB<->Serial Adapter.

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