Loco forward or reverse

[model-trains]

Hi guys,

 

I have 8 locos that all run forward and reverse correctly.

 

I have just purchased a new Bachmann Class 66 EWS loco, which wants to go reverse when I request forward and visa-versa. The loco has a driver in one end (front) and has lights so front is easily defined.

 

I am aware in iTrain that when the loco is facing forward on the track and the direct arrow on the layout does not match the direction of the loco, that I hold down the shift button and click the track arrow to change its direction to match forward on track and in the loco/train control. But when the track and the train control are both set to forward, the lights on the front turn red and the loco goes the wrong way.

 

Is there a way round this? Is there a CV to change the polarity of the loco?

 

I use iTrain with Digikeijs control DR5000

 

[Ray H]

CV29 should do the trick, but you'll need to look into how its value is calculated. That said, I believe that I heard a story that if CV29 is currently an odd number you should subtract one from its value. Conversely if CV29 is currently an even number you need to add one to its value.

 

Does that help?

[Dagworth]

55 minutes ago, model-trains said:

 

Is there a way round this? Is there a CV to change the polarity of the loco?

 

I use iTrain with Digikeijs control DR5000

Are you saying that the loco goes the opposite direction to what the lights are showing, so it has reds on the front and whites at the back no matter what you do? 

 

What decoder is fitted? 

 

Personally I didn't find the Digikeijs programming interface particularly friendly for more complex programming, can you program using JMRI as it will be a lot easier that way?

 

Andi

[jivebunny]

From the OP's initial post it sounds like it's just going in reverse when set to forward and vice-versa.

 

Very useful tool here from the 2mm Scale Association that you can use to not only calculate the correct value for CV29 according to the settings you need, but also to determine which settings are configured by first reading the value from the decoder, then entering it into the box and clicking the "BackCalc" button:

 

http://www.2mm.org.uk/articles/cv29 calculator.htm

 

Alan

Edited August 19, 2020 by jivebunny

[Brian]

Hi

To reverse the direction of travel of a DCC loco, use CV29 and add 1 to whatever is read currently in CV29. e.g. if you read 6 then make CV29 value 7, if it reads 38 make it 39 etc.  If it read an odd number - 7 or 39 for example reduce that value by 1

This CV 29 calculator is a useful item to bookmark. CV29 calculator link while its the 2mm scale Association the calculator applies to all scales using standard DCC decoders.

Edited August 26, 2020 by Brian
Edit ...Text added to the CV29 text

[34theletterbetweenB&D]

1 hour ago, model-trains said:

... The loco has a driver in one end (front)...

A little bit of plastic in the cab doesn't define the no 1 end. In UK practise the cooling group end is no 1 end. If your 66 moves with no 1 end leading and showing white lights when you select forward on the DCC system, then all is as it should be.

 

Which doesn't mean you have to conform of course, it's a free world...

[Nigelcliffe]

9 minutes ago, Brian said:

Hi

To reverse the direction of travel of a DCC loco, use CV29 and add 1 to whatever is read currently in CV29. e.g. if you read 6 then make CV29 value 7, if it reads 38 make it 39 etc.

 

 

BAD advice.    If CV29 were 7 already, and you added 1 to it, it becomes 8, which isn't likely to be the desired outcome. 

 

If using the calculator I wrote, referenced twice in the thread,  it shows why this "add 1" approach doesn't work out well.   

The calculator applies to all DCC decoders. 

 

( If I had a micropayment for the calculator page of 1p per use, I'd be able to afford a decent live steam garden railway by now..... ).  

 

- Nigel

 

[Dagworth]

7 minutes ago, 34theletterbetweenB&D said:

A little bit of plastic in the cab doesn't define the no 1 end. In UK practise the cooling group end is no 1 end. If your 66 moves with no 1 end leading and showing white lights when you select forward on the DCC system, then all is as it should be.

 

Which doesn't mean you have to conform of course, it's a free world...

Class 66 is the "wrong way round", number 1 end and thus "front" is the non-radiator group end.

 

From my reading of the OP it looks like the lights are always red at the leading end and white at the rear. I'm wondering if the decoder is 8 pin and plugged in backwards.

 

Andi

Edited August 19, 2020 by Dagworth

[jivebunny]

15 minutes ago, Nigelcliffe said:

( If I had a micropayment for the calculator page of 1p per use, I'd be able to afford a decent live steam garden railway by now..... ).  

 

- Nigel

 

 

Going slightly off-topic here, but how about setting up a Paypal donation button for those who wish to show their support?

 

Alan 

[Brian]

Of course if CV29 read seven then you would reduce that by 1 or if it reads 39 you would make it 38. I didnt make that clear!! Sorry  Post corrected.

 

Ray H points the way in a much earlier post here.

 

Of course if the link I provided in my original post to the CV29 calculator is used correctly then no such errors would be made!!

Edited August 26, 2020 by Brian
Updated to reflect change to original post I made

[34theletterbetweenB&D]

25 minutes ago, Dagworth said:

Class 66 is the "wrong way round", number 1 end and thus "front" is the non-radiator group end...

Oh good, I am non-conforming then. (From a purely practical perspective I wouldn't want to have to remember an 'odd one out': uniformity, that's simplest, and KISS is where it is at for bears of small brain like myself.)

28 minutes ago, Dagworth said:

..From my reading of the OP it looks like the lights are always red at the leading end and white at the rear. I'm wondering if the decoder is 8 pin and plugged in backwards...

I couldn't decode what the OP conveyed with any confidence, but felt that the idea of the driver representation position defining the leading end was not the best thought.

[model-trains]

1 hour ago, Dagworth said:

Are you saying that the loco goes the opposite direction to what the lights are showing, so it has reds on the front and whites at the back no matter what you do? 

 

What decoder is fitted? 

 

I know that iTrain is correct, it also helps knowing that  other locos are correct regarding forward and reverse.

 

The loco goes forward with the front lights on so I think the cv29 switch should solve the issue. At this stage the loco is brand new, you know the new I mean, just arrived can't wait to play new.   I have not read the CVs so still on address 3, so also not sure which decoder although it is an ESU with sound.

 

I need to read all the messages you guys kindly added, I went away for a brew and came back to more messages that I expected. You guys are very helpful. Thank you.

[WIMorrison]

Change CV29, if it is even then ADD 1 (one) to the value and if it is ODD then subtract 1(one) from the value

[model-trains]

1 hour ago, jivebunny said:

From the OP's initial post it sounds like it's just going in reverse when set to forward and vice-versa.

 

Very useful tool here from the 2mm Scale Association that you can use to not only calculate the correct value for CV29 according to the settings you need, but also to determine which settings are configured by first reading the value from the decoder, then entering it into the box and clicking the "BackCalc" button:

 

http://www.2mm.org.uk/articles/cv29 calculator.htm

 

Alan

 

Hi Alan,

 

No the loco goes forwards with front lights on, it just goes in reverse in iTrain, but I know iTrain is OK because 8 other locos go forward and backwards correctly.

 

Thanks for your help and the link I will look a after reading the CV's.

[model-trains]

55 minutes ago, 34theletterbetweenB&D said:

A little bit of plastic in the cab doesn't define the no 1 end. In UK practise the cooling group end is no 1 end. If your 66 moves with no 1 end leading and showing white lights when you select forward on the DCC system, then all is as it should be.

 

Which doesn't mean you have to conform of course, it's a free world...

 

 

Hi, 

 

I totally agree regarding the bit of plastic, the train driver, it was more of a comment but your reply made me laugh.

 

Thanks for your help.

 

[model-trains]

5 minutes ago, WIMorrison said:

Change CV29, if it is even then ADD 1 (one) to the value and if it is ODD then subtract 1(one) from the value

 

 

Will do thank you Iain.

[model-trains]

2 hours ago, 34theletterbetweenB&D said:

A little bit of plastic in the cab doesn't define the no 1 end. In UK practise the cooling group end is no 1 end. If your 66 moves with no 1 end leading and showing white lights when you select forward on the DCC system, then all is as it should be.

 

Interesting

 

I ask because I am not sure, which end would you say is the front of this loco?

 

There are two grills on the side in the picture, there is only one grill on the other side. The train driver, piece of plastic, is at the end with just 1 grill, the other end of the loco has the two grills, one each side

 

 

Bachmann Class 66 (With sound and lights)

 

Thanks in advance

 

Paul

Edited August 19, 2020 by model-trains

[34theletterbetweenB&D]

1 hour ago, model-trains said:

...which end would you say is the front of this loco?

See this reply:

3 hours ago, Dagworth said:

Class 66 is the "wrong way round", number 1 end and thus "front" is the non-radiator group end.

The radiator end is the one with the big grille or fans on the roof of the diesel.

[model-trains]

1 hour ago, 34theletterbetweenB&D said:

See this reply:

The radiator end is the one with the big grille or fans on the roof of the diesel.

 

 

As I thought thanks

 

I will read the CV's tomorrow and change CV29

 

Paul

[RAF96]

If the decoder is 8-pin and plugged in backwards the lights will not work at all.

If 21-pin you cannot easily plug it in wrong as socket has a blank pin.

[Michael Hodgson]

On 19/08/2020 at 14:55, WIMorrison said:

Change CV29, if it is even then ADD 1 (one) to the value and if it is ODD then subtract 1(one) from the value

 

What he said!  

 

Beware that some of the other posts on here are wrong.  CV29 contains some other settings you DON'T want to change.

 

And if your DRS 5000 is not helpful directly in pogramming the settings, you could find it easier to do using itrain,  

 

This is how it works.

If Bit 0 of that CV is set to zero (which is usually the case, and CV29 is therefore even) and the loco pickup is wired with the correct polarity, the train will run normally.  As the loco is behaving as you say, one or other of those assumptions is false.

If Bit 0 is set to 1 (therefore cv29 is odd) is set it will go the other way.  This is a feature which saves you taking the loco apart to get at its innards to correct a wiring error.

 

As the loco is behaving the wrong direction, ALL you need to is CHANGE that bit setting. 

That means ADD 1 if cv29 is even, but SUBTRACT 1 if it has incorrectly been set to odd.  If you do anything else to CV29, you could affect other settings including the loco address, or how the loco behaves in the event that you put it on a DC layout.

 

Edited August 22, 2020 by Michael Hodgson

[model-trains]

On 22/08/2020 at 16:57, Michael Hodgson said:

s the loco is behaving the wrong direction, ALL you need to is CHANGE that bit setting. 

That means ADD 1 if cv29 is even, but SUBTRACT 1 if it has incorrectly been set to odd.  If you do anything else to CV29, you could affect other settings including the loco address, or how the loco behaves in the event that you put it on a DC layout.

 

 

Very helpful Michael thank you.

 

[KingEdwardII]

I recently had to make this change for the Zimo MX638D 21-pin decoder I installed into my new Heljan 47xx 2-8-0. The default installation had the loco going in reverse when "forward" was selected on the controller. In my case, bit 0 of CV29 was initially "0" so I flipped it to a "1" by adding 1 to the original value of CV29. It is important to leave the value of the other bits of CV29 unchanged, since they affect other functions of the decoder. Now my 47xx goes the right way when I select "forward" on the controller!

 

Mike