The Dummies Guide. - Cv's - Massoth

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Following various threads on this esteemed forum I will start the dummies guide to digital.
This thread deals with CVs only and Massoth only. I am sure most of the information can cross over to other makes but lets keep it simple.
This thread is about CVs, for Massoth - not about HOW to change them or WHAT KIT to use. Hopefully, other threads will deal with that. It is based on the XLS decoder but I think most of it is relevant to all Massoth decoders. Please note, other manufacturers use some CVs differently.
This thread WILL BE HEAVILY MODERATED to keep it as clear and simple as practical, it may also get locked from time to time. Please feel free to add you 2 pennys worth but don't be disappointed when it is plagiarised or just deleted.
Also - I can make mistakes!

It has been suggested that I indicate the voltage levels associated with various CV values, also the degree of effect that a change would have. A laudable idea but to be honest I don't have much of a clue. I do all my adjustments by trial and error or by copying something similar. What I would say is, remember the original settings and go slowly - a small change can make a marked difference.
 
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INDEX.

This post will be regularly edited to create an index.
Post 3 - What is a CV
Post 4 - CV1 - Address (short address)
Post 5 - CV29 - NMRA configuration. (direction, speed steps, long address, digital or analogue, driving curve.
Post 6 - CV17 and 18 - Address (long address)
Post 7 - CV2 - Starting Voltage
Post 8 - CV 3 - Acceleration time.
Post 9 - CV4 - Deceleration time.
Post 10 - CV5 - Top Speed.
Post 11 - CV6 - Mid speed.
Post 12 - CV7 - Decoder reset.
Post 13 - CV9 - Motor frequency
Post 14 - CV13 - Function outputs in analogue mode.
Post 15 - CV49 - Massoth configuration.
Post 16 - CV50 - Lighting dimming/voltage
Post 17 - CV51, 52, 54, 56, 113, 115, 117, 119. - Switching command allocation.
Post 18 - CV53 and CV112 - Smoke voltage. Dimming/voltage for F1 and F2 / F3 and F4.
Post 19 - CV55, 57, 114, 116, 118 - Special functions for F1 to F5.
Post 20 - CV57, 114, 116, 120 - Expanded special functions. F2, F3, F4 and F6.
Post 21 - CV58 - Pause time when reversing direction.
Post 22 - CV59 - Half speed for shunting.
Post 23 - CV60, 61, 62, 63, 64. - Load control re-adjustment factors.
Post 24 - CV's 67 to 94 - Programmable driving curves in 28 steps.
Post 25 - CV121 and 123 - F7 and F8 switching.
Post 26 - CV124 to CV127 - RC servo control on F7
Post 27 - CV129 and 130 - Time delay with power buffer.
 
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What is a CV.
CV stands for Configuration Variables. Basically each CV has an identifing number and that number can be assigned differing values. Which values will work and what they do differs for each CV number.

So,
Each CV is identified by its NUMBER.
Each CV is allocated a VALUE

It is these VALUES that we can configure and that enable us to customise our railways.
 
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CV1. Address - short.

Value range 1 - 127

This is the address number for your individual loco. you can pick any number in the range for each of your locos and follow your controllers instructions to allocate it.
The default value from the manufacturer is usually '3'.
Many older systems will only deal with values (addresses) 0 - 23
The address '0' is an oddity. On some systems it will allow a non digitally fitted loco to work on a digital layout. Some manufactures promote this (LGB) and some strongly recommend against it (Piko).
0 is not a valid value for CV1.

See also CV29
 
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CV29. NMRA Configuration.

Value range - see below.

We are going to jump to CV29. This is an important CV and controls several differing things.
Unfortunately, this makes it a bit complicated but its an important starting point to understand this one.

The CV values control 'bits'. If you remember binary numbers from school it will help.
A CV can be divided into 8 'Bits'
Each binary number controls each bit. A bit can be on or off.
The value '0' is always 'off'.
Value 1 turns bit 0 'on'.
Value 2 turns bit 1 'on'.
Value 4 turns bit 2 'on'.
Value 8 turns bit 3 'on'.
Value 16 turns bit 4 'on'.
Value 32 turns bit 5 'on'.
Value 64 turns bit 6 'on'.
Value 128 turns bit 7 'on'. (bit 3,6 and 7 are not actually used in CV29).

You set the value of CV29 by adding up all the 'on's that you want and programming this total to CV29

Bit 0 controls driving direction. 'on' will go one way, 'off' will go the other. If your loco is going the wrong way you need to change bit 0. Either add or subtract 1 from the total value.

Bit 1 controls the speed steps that your loco can accelerate through. Older decoders and base stations would handle 14 steps, newer ones will handle 14, 28 and 128. You often need the base station and your decoder on the same setting for best results. For 14 steps use a value of '0', for 28 and 128 use a value of 2

Bit 2 decided whether your loco will run on digital only (value 0) or digital and analogue (value 4). 4 is the most common setting but certain digital requirement may dictate that analogue is turned off.

Bit 4 selects the driving curve. You can have the internal curve or a programmed curve. The internal one is a default speed for each speed step, whilst the programmed one lets you dictate the speed for each step. As an example, a shunting loco may have more steps allocated to slower speeds and fewer to high speeds - thus allowing more control over speed when shunting. This is getting a bit advanced so ignore it for now. It's CVs 67 to 94 for when your feeling confident and adventurous.

Bit 5 selects short address (as in CV1, above) or long address. Short address has the value of '0' and long address is '32'

Take it steady and at one step at a time, its not difficult, it just looks overwhelming.

Example: we want our loco to move the standard direction (value 0), to use 28 speed steps (value 2), to be ready for digital and analogue operation (value 4), use the internal driving curve (value 0), and a short address value (value 0)
Add them up and your value for CV29 is 2 +4 = 6. Now, if the loco moves the wrong way we need to change bit 0 to 'on' - using the value of 1. CV29 is now 1+2+4 =7


NOTE; You will come across references such as 'bit 5 being equal to 1'. This only means that bit 5 is 'ON'. The programming value is still 32 (for bit 5) not 1.
 
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CV17 and 18. Address- Long.

Value - as below.

Long address codes can be used to allocate loco address from 128 to 10239.

To access the 'long' address codes we need to set bit 5 in CV29 to on. (see above - add 32 to the total value of CV29)

The address is now set in CV17 and 18. Most controllers will set both CVs for you when you select an address. Most will change CV29 for you as well.

No need to read this bit but if you really want to know how CV17 and 18 are calculated here goes.
CV17 is the address you want divided by 256 and rounded down to a whole number. CV18 is the address you want minus the value for CV17 when multiplied by 256

Neil Robinson supplied this link to calculate long address codes. Thanks.
http://www.2mm.org.uk/articles/cv29 calculator.htm
 
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CV2 - Starting Voltage.

Value range - 1 - 255
Default - 2

This CV sets the voltage needed to start the motor turning. It is usually set to a value so that your loco moves off on speed step one. The default value is 2. Higher voltages before moving off may be required to power accessories on a loco before the loco moves. Alternatively, if your loco will not move on speed step one or two - look at INCREASING this CV a little.
 
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CV3 - Acceleration time (works in analogue use as well)

Value 1-255
Default 3

This CV controls how fast a loco will accelerate. If you wack the controller to full speed the loco will accelerate to that speed in a controlled manner. The higher the Cv setting the more gradual the acceleration
 
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CV4 - Braking time (works in analogue use as well)

Value 1-255
Default 3

This controls how rapidly a loco will decelerate. If you close the controller quickly the loco will gradually come to a halt. The higher the CV value, the more gradual deceleration will be.

On modern decoders with brake squeal noise, adjusting this CV can make quite a difference to the automatic break squeal effect. Usually, the higher the value, the better the effect but too high makes the loco difficult to stop exactly where you want it to.


AlanL contributed - The default settings of 3 are virtually instant. When I was setting up automatic running, with these cv's at default, the trains would start and stop un-realisticly abruptly. I now have these set between 25 and 40 to give a more gentle start and stop. Even at these values the start/stops are quick.
 
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CV5 - Top Speed. (works in analogue use as well)

Value 1-255
Default 200

This CV will limit the maximum speed (motor voltage) of a loco. Great for kids use!
The lower the CV value the slower the top speed.

COMPLICATED NOTE: The default is set below the maximum speed to allow 'Back EMF/Load Control' to work correctly. If your loco slows on a hill or curve the motor voltage is automatically increased to maintain speed. If its set to maximum (255) there is no voltage left so Back EMF cant work.
 
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CV6 - Mid speed point.

Value 1-255
Default 50

This CV sets the speed of the loco at the middle speed step (7, 14 or 64). If the value is half of top speed (CV5) all speed steps will be equal. However, If the value is less than half, the mid speed point will drive more slowly and the lower speed steps will all drive more closely together giving greater low speed control (this is the default).

You can program your own speed curve in CVs 67 to 94 and by changing bit 4 in CV29. This will deactivate CVs 2,5 and 6.
 
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CV7 - Decoder reset.

Don't do it.
OK, if you have really buggered things up and you cant get anything to work, it might help.
I have never had the need to do a reset. Not all resets work - I have heard of a few (but not at all many), horror stories of decoders saying their last good byes.

But if you must, and I do know people who seem to do them all the time.

Consult your documentation - these details are the ones that seem to change from month to month.
My XLS book says there are 5 options and then lists 6!

Value 55 - reset basic settings
Value 66 - reset motor setting
Value 77 - reset lights and functions
Value 111 - reset CVs 131 to 167
Value 122 - reset Cvs 171 to 199
Value 133 - reset CVs 200 to 212

as I said, I have never done one, so, as far as I am concerned, your on your own matey.
 
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CV9 - Motor frequency.
Value range 0 - 3
Default - 0

The lowest value (giving the highest motor frequency) is usually the best. Some cheaper motor may run rough or hot at the high frequency so experiment with other values if you feel the need - I never have.
LGB Buhler Motors should definitely be left on value 0. I have heard of some Piko motors running better on other settings but my one Piko loco is still on 0.
My personal advice - don't touch it.
 
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CV13 - Function outputs in analogue mode.

Default 3 (F1 and F2 always on in analogue mode)

We are back to 'bits' again. See CV29, post 5. Various functions (lights usually) can be switch to on for when running in analogue mode.

For your locos functions, refer to the loco documentation.

To switch on F1 use value 1
To switch on F2 use value 2
F3 4
F4 8
F5 16
F6 32
F7 64
F8 128

for off use value '0'.
Add up all the bits and that is your Value for CV13
 
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CV49 - Massoth configuration

Values - as below.
Default - 31

More Bits.

Bit 0 - Parallel data (P) - value 0, parallel and serial - value 1. Default 1
Bit 1 - Digital load control off = 0, on = 2. Default 2
Bit 2 - Analogue load control off = 0, on = 4. Default 4
Bit 3 - F1 output standard = 0, P update fast pulse string output = 8. default 8 (only works with Bit 0 on (Value 1)
Bit 4 - Electronic parking brake off = 0, on = 16. Default 16. Only works when stationary.

Serial/parallel - methods of sending signals to your decoder. Serial is the older version. 'P' indicates parallel
'Load Control' . If your loco slows on a hill or curve the motor voltage is automatically increased to maintain speed.
Fast Pulse string - fast method of sending messages to your decoder. Only works on 'P' .
Parking brake. A heavy train on a slope will be held by a low current to the motor.
 
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CV50 - Lighting voltage/dimming.

Value 1-32
Default 32

The value 32 = full track voltage going to your lights.
A lower value will give proportionately lower voltages.

So, if our central station is outputting 24V and we want our lights to run at 5V

32 divided by 24 = 1.333 x 5 = 6.666.

So a Value of 7 would work. But not wanting to blow bulbs with a high voltage, 5 or 6 might be better. I tend to use 5, this gives a slightly yellowy colour too that I think looks right.

NOTE; The default is full track voltage. Lights are often only 5V. If your lights are connected directly to your decoder reduce the voltage (this CV) before switching on. Many locos have integral circuit boards that reduce the voltage for lights (and smoke units). If this board is left in place you may not need to reduce this CV, but if your unsure it's best to reduce it first and increase it later if required.
 
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Confused yet? You soon will be.

CVs 51, 52, 54, 56, 113, 115, 117, 119
Switching output command allocation.

These values allocate the function buttons on your controller to specific functions/lights on your loco.
Values 0-16 tie F keys 0-16 to this CV.
Value 64 = The function is on only when going backwards. (when also switched on)
Value 128 = The function is on only when going forward. (when also switched on)

As an example, front lights (CV51) are switched on with key '0' so value = 0 and come on in forward motion only so value =128 - total value =128

CV54 is often used for smoke control. Function key 7 is usually allocated to smoke so CV54 would be Value = 7, which is the default. (And just to confuse you, CV54 is called F1).

CV51 - Front lights - default 128 - Key 0
CV52 - Rear lights - default 64 - key 0
CV54 - Function 1 (smoke?) - default 7 - key 7
CV56 - Function 2 - default 2 - key 2
CV113 - Function 3 - default 3 - key 3
CV115 - Function 4 - default 4 - Key 4
CV117 - Function 5 - default 5 - key 5
CV119 - Function 6 - default 6 - key 6
 
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CV53 - Dimming / Voltage Reduction for F1 and F2 (CV54 and 56).
CV112 - dimming/ Voltage Reduction for F3 and F4 (CV113 and 115)

defaut 32 - full track voltage.

For CV53.
This can be used to reduce the voltage supplied to F1 and F2. Smoke is usually on F1 (CV54) so this can be used to adjust for a 5 Volt smoke unit - See CV50 (post 16) above for values.

CV53 controlls both F1 and F2 but-
add 64 to the value and F1 only is effected
add 128 to the value and F2 only is effected

(I THINK !, CAN ANYONE CONFIRM MY INTERPRETATION)

For CV112.
Exactly the same but for F3 and F4 (CV113 and 115)


Some users advise against connecting a smoke unit directly to your decoder because of a possible overload damaging the decoder. The details are beyond the scope of this thread but for more info just search or ask on the forum.
 
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CV55, 57, 114, 116, 118.
Special functions for F1, F2, F3, F4 and F5.

Default 0

These CVs can be used to give lighting effects to F1 to F5.

Value 0 - standard operation.
Value 1 to 15 - Flashing lights. each additional value adds 0.25 seconds to the flash interval.
Additional value of 64 gives a short term function. Function will switch off after time set as above.
Additional value of 128 gives an asymmetrical flash (1/3 on, 2/3 off)
Additional value of 192 gives an asymmetrical flash (2/3 on, 1/3 off)
 
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CV57, 114, 116, 120.
Expanded special functions for F2, F3, F4, F6

Default 0

An additional value of 16 to CV57 will link F2 with F1 for alternating flashing of lights.
An additional value of 16 to CV116 will link F4 with F3 for alternating flashing lights.
An additional value of 16 to CV120 will link F6 with F5 for alternating flashing lights.
An additional value of 30 to CV114 will give an electrical pulse simulation for pulsed smoke generators in the absence of a sensor. (Not for use with axle sensors - follow the instructions with your sensor)
An additional value of 31 to CV116 gives control of charging for a power buffer in programming mode. (Power buffers interfere with programming) F4 can be used to turn off the charging. Check with your power buffer documentation - I have never done anything in this area so you are on your own.
 
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