Help - setting the F2 brake control on a Zimo MX617N

[Ollie123]

Hello

 

I have just had installed (hardwired) into an older Farrish loco a zimoMX617N decoder, I am struggling to set up the F2 brake in CVs 309 and 349, none of the values match the online manual from Zimo and do not work.
 

CV 7 says 0037 so am not sure I have the firmware to do this as the manual says the software for this function is only valid above 33.23

 

If anyone has any ideas tips for this it would be much appreciated 

 

thanks 

 

Ollie 

[jpendle]

Hi,

 

CV7 = 0037 so that is version 37.nn, the subversion (the numbers after the decimal point) are read from CV65. So your decoder is at a higher version than 33.23.

 

The default values of CV's 309 and 349 are 0, and the default value of CV4 is 1. All these CV's will need to be adjusted to get the a brake key to work.

 

When you say 

 

6 hours ago, Ollie123 said:

none of the values match the online manual from Zimo and do not work.

 

what do you mean?

 

Regards,

 

John P

[nightmail]

I have the same problem with my Digitrax Zephyr. It turns out it won’t programme CVs higher than (i think) 255.

 

could that be the issue for you too?

 

There is a workaround, but that didn’t work for me either!

 

[Ollie123]

Hi John

 

Thanks for replying, 

 

When I try and change cv 309 it should be only between 1 and 28 ie 2 would make F2 work, when I input 2 it goes to something like 198.  I have version 37.22 so should would work.  
 

Having pulled my hair out yesterday afternoon searching the net, it seems if you adjust cv 156 to 2 the brake function seems to work on F2, but very rapidly, if I adjust as well cv124 to 2 this problem seems to reduce itself.  I will need to adjust cv 3,4,5 now 

 

Ollie

[jpendle]

Hi,

 

CV's 124 and 156 let you turn momentum off, i.e. the decoder ignores what's in CV's 3 & 4. So if you set CV156 to 2 then pressing F2 will turn momentum off and any speed change that gets sent to the loco happens immediately. I would set CV's 124 and 156 back to 0 and start again.

 

Now I have never done this myself so I may get this wrong.

 

First set CV4 to 50, this would mean that the loco would take 45 seconds to slow down from top speed to a complete halt.

Then set CV309 to 2 and CV349 to 5.

Now if you run the loco at max speed and then set the speed to 0, it should coast for 45 seconds, if you press F2, then the loco should brake harder. If you keep F2 activated then it should stop in around 4.5 seconds.

 

Oh, what DCC system are you using?

 

Hope that helps.

 

Regards,

 

John P

Edited September 12, 2021 by jpendle
Correction

[Ollie123]

Hi

 

Be prepared to get confused as I am.

 

Your totally right about what you said, setting CV309 to 2 etc., I was trying this way before hand with no success 

 

When I try to change CV309, if I put "2" it goes to 198 after writing - it should only allow between 0 and 28

CV349 does the same.   

 

If I change CV124 to 2 and CV156 to 2,  set the throttle to 99% the engine will accelerate depending how I set CV3, and if I reduce the throttle to 0% the loco coasts to a stand depending how CV 4 is set, if you adjust these obviously the loco does different accelerating and de accelerating rates.  Now, if I hit F2 with this the loco will start to brake a lot faster with me controlling it take my finger off F2 and it goes back into coasting to a stand, hold F2 down, it stops a lot faster

 

Am using the Digitrax evolution express advanced

 

Any ideas?

 

Thanks again 

 

Ollie

[Nigelcliffe]

Stuff for Ollie.   
As you have a Digitrax Evolution system, it should have a USB connection on the front.  Cable from there to a computer (Windows, Apple or Linux), and install JMRI.  That makes JMRI/DecoderPro an option for changing CV's, recording what's set in every loco, and saves a lot of handset faffing to make changes.

( I'm starting to wonder if there is a systematic error with decoder readings above CV255 with some Digitrax throttles and Zimo decoders, because this isn't the first time I recall this being reported for CVs above CV255). 

 

 

The CV124/CV156 combination is a "poor mans" version of the brake key.  It probably does a fair bit of what's needed, as when the key is pressed, the acceleration/deceleration is set to 1/4 of the CV3/CV4 values (by CV124=2), and the use of CV156 determines which key (=2 = F2).   

 

The full-version of the brake key (CV309/CV349) is similar, except that the user can specify the deceleration rate, rather than being limited to 1/4 of the CV4 value.   

 

 

So, from here, there's two ways:   Decide its working well enough with the 1/4 value, and stop looking for more,  or keep investigating to find out what's going on.   

 

 

[Ollie123]

Thanks Nigel for the tips

 

I have spend a few hours today setting JMRI on my Mac book, and set CV309 to 2 on there, when I read it on the digitrax system it still says CV309 is 130 but the brake function works with F2 now properly as I have reset CVs 124 and 156 back to 0.  

 

thanks again 

Ollie

[Nigelcliffe]

There was some stuff elsewhere suggesting that firmware updates to Digitrax systems fix various issues.  Don't know if your system (handsets or command station) need updates or not.  Suggest discussing with the supplying dealer before doing any update (and you may need a Windows PC to run the Digitrax updating tools).  

 

- Nigel