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dcc 308 error decoder 2 months old Track and electrical/DCC
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Regular poster 165 posts dennis461 Regular poster 165 posts
dennis461
 
 
I've got an XL systems decoder (Manufacturer for MRC).
Was working good, and I was fooling around with the settings for back EMF speed control.
Changing them on program track, going back on the MAIN, running a train forward- backward- fast-slow.
I'm using JMRI, decoder pro with an Arduino and motor shield.

The loco, Athearn F7 stopped running in reverse!

Figured I needed to reprogram, but.

Decoder pro giving me an error 308, No acknowledge from locomotive .
Tried the single CV writing, same error.
Tried another locomotive on the program track, and decoder pro finds everything on that loco.
Checked for F7 decoder connection to rails, and any obvious short but did not find any. (Opened it up)

Is the decoder trash now?
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CandOfan Prolific poster 1,554 posts
CandOfan

Check the connection between

Check the connection between the computer and the track (I think that's the Arduino/motor shield in your config). The 308 error usually means that the thing that DecoderPro is trying to use to talk to the track is somehow not communicating(or alternatively, that thing is having trouble talking to the programming track.

Oh- and are you using a programming track or programming on the main? 308 seems to happen a lot more on dedicated programming tracks.

Modeling the C&O in Virginia in 1943, 1927 and 1918
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Jim at BSME Prolific poster 2,110 posts
Jim at BSME

Options

You could always try a decoder reset, lots of decoders it is writing CV8 with an 8, also found this reference for MRC decoders, write CV125 with a 1.

If you have an actual throttle and DCC system as opposed to JMRI/Arduino/Motor Shield, I would use that to attempt to reset the decoder.

As far as I know MRC offers a lifetime warranty on all their products, just have to contact them for an RMA number to send it back for repair, don't know what the costs are, I think just shipping to them.
- Jim B.
Baltimore Society of Model Engineers, Estd. 1932
O & HO Scale model railroading
Check out BSME on: Facebook, Instagram
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dennis461 Regular poster 165 posts
dennis461

Connections are fine, layout

Connections are fine, layout and control/programmer works on 2 other locos.

I'm using a separate program track, two rail gap siding on main layout and can toggle it MAIN or PROGRAM.

Won't accept any CV changes.

Going to put it aside and put a Digitrax  in a SW1500.
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blindog10 Prolific poster 3,329 posts
blindog10

Sounds like a blown motor FET

The fact that the loco won't go in reverse suggests two possibilities.  One, you've programmed the decoder (accidentally) to not apply power in tge reverse direction.  I don't know if that's even possible with an MRC decoder.  Two, and more likely, the motor FET (Field Effect Transistor) that feeds the reverse direction has failed, or has a bad solder joint.

Since MRC decoders are known to be stubborn, I would try a reset (CV125=1) in OPS mode on the mainline.  Then see what it does.

And while I don't think it will help here, I have "woken up" sleepy MRC decoders by applying 9 volts from a battery to the wheels.

Good luck.

Scott Chatfield
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marcfo68 Frequent poster 656 posts
marcfo68

. . .

If it still runs in a forward direction, it should be programmable.  Try the CV125=1 reset as others mention.

If you are still getting the 308 error then the decoder might be toast.  308 is " No ACK seem  from the decoder " error condition. That indicates DecoderPro saw a load (no 301 error),  " something " on the program track but that " something " is not responding with an ACK pulse to program commands.

Some may not be aware of this listing of potential  JMRI DecoderPro error codes it can throw :

JMRI Error Codes

301 - no locomotive detected

The command station has reported that it doesn't see a locomotive on the programming track.

This can happen if the locomotive isn't making good electrical contact or if there's a wiring fault in the locomotive.

302 - programmer busy

The command station has reported that it's busy doing something else, and can't do any programming right now. This usually means that some other part of the DCC system is doing a programming operation, e.g. a hand-held throttle.

Some DCC systems can't do ops-mode programming (programming on the main) while also using the service mode programming track, in which case they'll return this error message.

303 - requested not implemented in command station

This means that JMRI has requested the command station do something that it doesn't support.

This is not supposed to happen, as JMRI should disable programming modes that the command station can't provide. If you do see this message, please report the circumstances on the JMRI users Group.

304 - aborted by user

The user has requested that the read or write operation stop early.

This is considered an error, because the program doesn't know whether the decoder actually saw the operation complete or not.

305 - confirm failed

Some command stations allow you to "confirm" the content of a CV, rather that read the value from it. In general, this is faster than doing a complete read. If the value in the CV doesn't match the expected value, this message is issued. It's considered an error because if the values don't match, we know that we don't know the correct value for the CV contents.

306 - timeout talking to command station

The program did not hear back from the command station when it expected to.

This is by far the most common error message when people first start using JMRI. In that case, it usually means that the connection to the command station isn't correct. This could be a problem with the cable(s) making the connection, or a problem with how the preferences are set. Picking the wrong serial port is particularly common.

Once JMRI is working properly, this error may occasionally happen due to a transient error. DecoderPro generally will retry it successfully in that case.

307 - Unknown error

An error has happened, but JMRI doesn't know enough about it to be able to report more detail.

In general, JMRI is pretty good at deciphering what went wrong, and this message isn't very common. If you do see this message, please report the circumstances on the JMRI users Group.

308 - No acknowledge from locomotive

At the end of a CV read or write operation, the locomotive replies ("acknowledges") to the command station using a pulse of current.

If that pulse isn't seen, some command stations provide this error message. It could be due to poor electrical connections to the programming track or within the locomotive. It could also be that the decoder doesn't support readback.

Some decoders, particularly certain sound decoders, draw so much current that the reply pulse isn't detected by the command station. In that case, one of the various "programming boosters" may solve the problem.

309 - Short Circuit on Programming Track

The command station has reported seeing a short circuit on the programming track. That prevents programming operations.

Check the electrical connections to the programming track, and also within the locomotive.

310 - Sequence Error

For some reason, the programming operation ended early and the command station returned to normal mode (left service mode) before it should have.

This error can occur when some operations are performed in JMRI durring programming. Turning track power on durring a programming operation on an XpressNet is one example of how to create this error.

If you haven't performed any operations durring your programming sequence, this error, might indicate that you've selected the wrong command station type in the preferences. Check that. If that's correct and it's still happening, ask for help on the JMRI users list.

311 - Communcation Error Between PC and Command Station

The data between the PC and the Command Station was corrupted and the corruption was detected before the Command Station processed the request.

If this error occurs frequently, this error might indicate a problem with the connection between your computer and the command station or an issue with your system interface. Wireless connections are more prone to this issue than connections with physically connected cables.

Marc

 
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dennis461 Regular poster 165 posts
dennis461

Would not take a CV125

Would not take a CV125 reset

 Just installed a Digitrax in a SW1500 with no problem

 The XL is toast, I'll not buy another.
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Jim at BSME Prolific poster 2,110 posts
Jim at BSME

repair options

It might be worth a try to see if either MRC or XL Systems will repair/replace the decoder.

MRC: mrcsupport@modelrectifier.com

XL Systems: http://xlsystemsdcc.com/contact-us/
- Jim B.
Baltimore Society of Model Engineers, Estd. 1932
O & HO Scale model railroading
Check out BSME on: Facebook, Instagram
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dennis461 Regular poster 165 posts
dennis461

"And while I don't think it

"

Quote:

And while I don't think it will help here, I have "woken up" sleepy MRC decoders by applying 9 volts from a battery to the wheels.

Good luck.

Scott Chatfield"

I put it aside for a few days, then before ripping the decoder out I tried straight DC on another portion of my layout. It did not light up or run, FWD or REV.

Put it back on the programming track and Decoder Pro found it. Wrote a couple of CV's, and it is running again??????

Now to put wiring back in place,

IMG_4413.JPG 

Thanks Scott

 

 
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joef MRH Founder 17,528 posts
joef

MRC decoders ...

Quote:

Just installed a Digitrax in a SW1500 with no problem

The XL is toast, I'll not buy another.

The XL is an MRC decoder ... here's a thread discussing experience with the XL decoder line ...

https://www.modeltrainforum.com/threads/any-experience-with-xl-systems-sound-decoders.191070/

The general consensus is MRC makes great controllers and their accessory products rock. But their decoders, not so much, they tend to not have a great service life.

Joe Fugate​
Publisher, Model Railroad Hobbyist magazine

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Read my blog
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