Hornby Select ‘FE’ error code

[Luminaire]

I’m using a Select (latest firmware) as an xpressnet device plugged into another (non Hornby) command centre. On power-up the select flashes ‘FE’ for a few seconds before showing ‘CE’

After this the usual ‘walkabout’ stuff happens and the select can control locos as usual perfectly fine.

Im wondering if anyone has more info about the ‘FE’ code in particular as I can’t find any info on it anywhere. (I know the CE is an xpressnet command error, presumably caused by Hornby implementation of xpressnet not being quite the same)

To be honest I’m impressed the select works flawlessly after those initial errors - I’m just curious as to what that ‘FE’ is about.

[96RAF]

I have never seen FE on the Select screen in any mode and can only think it is being sent as part of the handshake with your alien master controller. CE as you say is reporting a comms error as may be expected connecting to a stranger.

If you tell us more about the setup someone with the same kit may be able to try it and report back.

[Luminaire]

Sure, I’m always conscious this is a Hornby forum so like to keep that part of the setup as the star of the show, but it’s a Roco Z21 (Black) it’s connecting to (via a R8266-type cable which was previously used for select-to-elite with no problem).

Your handshake theory sounds about right as once those errors have cleared the info seems to flow in both directions flawlessly for controlling locos so the actual ‘control’ xpressnet comms seems fine.

Maybe FE is ‘Foreign Entity’ reserved for when a german command station is detected (joking!)

[96RAF]

I have had a trawl of the Z21 manual and other associated data on the Z21.eu site but no clues there.

The only F code on the Select is Fd i.e. Forward direction so maybe the alien handshake is either looking to set this as a default or trying to match last set direction on the master to slave loop and failing thus flagging a new pseudo error code.

All total finger in the air guess work by me.

[Rog RJ]

FE Fatal Error?

[Luminaire]

@RAF - at this point guesswork is the best any of us have so meh, it works for me :)

@rog - haha ‘Fatal error’ was my first thought when I saw it too. My heart did a little tumble but then it worked.

Maybe ‘format error’ or something. I may just email Hornby support. I doubt they’ll give much info given the third-party hardware involved but hopefully they can shed some light on the ‘FE’ at least.

[Luminaire]

So Hornby tech support have come back (very quickly!) to say ‘FE’ means an internal short.

Very interesting that this should happen AND the unit still work, which is testament to the idiot-proofing Hornby build into their kit for people like me.

[96RAF]

Interesting. FE sounds terminal if the cable is cross connecting the Select with the Z21 internally to give a short. No wonder it then reports Comm Error but why it still works is an unknown without having the Z21 wiring schematic to compare with the Select, unless the Z21 has a pseudo reverse loop facility on the comms side to swap polarity if required - doubt it though.

The R8266 cable is a four wire config so it is only passing walkabout data.

The R8236 cable has six wires and feeds the DCC signal to a booster down the outer wires.

It is the possibility of cross talk twixt the outer wire pair and the inner wire pairs that usually fouls up and slows down reliable data flow if the wrong cable is used.

[Luminaire]

I was just reading Chrisaf’s great guide on stay alives and something he mentions in there struck me as possibly what’s happening here. He mentions that an empty capacitor initially looks like a short circuit as it draws current to fill up. Then, when it’s full it changes to look like an open circuit. This could explain how something is triggering a short warning and then clearing itself.

This feels like a good excuse to buy a new multimeter and take something apart. Very happy.

[96RAF]

Your starter for 10 . .

http://www.halton96th.org.uk/page11.html

Pinouts on the Select RJ12 ports are:

1. Boost Neg
2. Ground
3. Xpressnet Rx
4. Xpressnet Tx
5. Vcc 12v
6. Boost Pos
7. Your meter +/- indicator will tell you which is which if you connect for voltage across pins 1 and 6.

Compare with your Z21 to cross phasing.

Of interest does the FE then CE flag show if the Select is plugged in with Z21 already powered up and/or if plugged in and then the Z21 is powered up.

I have a ‘scope grab of the Elite Xpressnet port somewhere, I will try to dig it out.

Edit: It was part of a write up I did for Pico-Tech but it was only comparing the Boost output with Pins 1 and 6 on the RJ plug not the Xpressnet output on pins 2-5.

[Luminaire]

Cheers for that, really helpful.

So, after some fiddling:

Plug-in order and power-up order makes no difference - it’s exactly the same in all scenarios.

Connecting with only the 12V power pins wired results in no FE error (CE still happens of course as there’s no data Rx/Tx at all). Which suggests whatever it is it’s not the supply power causing the FE (something of a relief).

Reconnecting Rx and Tx but reversing them means no FE either, and of course a CE and no control of anything (as expected given the polarity of a balanced pair matters so it’s basically the same as no data at all)

So somehow the internal short is related to the data signal when wired normally. Which seems…weird.

I’ve reached the limit of my tools and knowledge without the ability (for now) to inspect the physical and data layers of the data signal, but it’s been fun to establish the Select DOES seem to work as an xpressnet throttle despite some quirks.

[96RAF]

Note that while Pin 5 is at 12V via a choke, it is also connected to Pin 2 Ground via a 100nF capacitor which may be the culprit is all this.

Select also works as a main controller in Railmaster when connected by the Select-a-Link beta cable that I have, which is USB at the PC end and RJ12 at the Xpressnet end, so that part of the comms loop is intact.

Here I am setting up a TTS decoder in the test rig, before RM was updated to recognise all Select functions.

[Luminaire]

It’s a shame the select/rail master link didn’t go into full production as it seems a good combo.

Ive discovered that hitting ‘stop’ right after power up skips the FE and CE errors and goes straight to working normally.

At an educated guess I’d say the select needs to figure out which of its many setups it’s in when the power comes on, and since hitting ‘stop’ causes an xpressnet message out to AND back from the CS it’s causing the select to enter the right mode quicker.

The internal short error almost feels like a red herring here. That said if it does go ‘pop’ I’ll be sure to report here.