Three point speed Table CV2/6/5

[Robert Frey]

To find CV2/6/5 at target speeds of 5/30/60 Mph, try the following procedure. With a DCC Locomotive, measure Mph at the true full throttle speed. Then program CV2= 64, CV6= 128 and CV5= 218. Now measure your Mph Scale speed at the 15% reduced full Throttle, Mph at one-half Throttle (128), and the Mph at the first step (64). Plot the three points Mph Vs Decimal Numbers and draw two straight lines through your three points. (Note that 60 Mph is actually 88 Feet per second in 1:1 scale.)

The first estimate of CV2/6/5 can be read on a line at speed points: 5/30/60 Mph. (For example: at the true full throttle an HO DCC Loco. speed was 75 Mph (4.8 sec. in 73 inches), at Mid. Throttle it was 45 Mph (4.0 sec in 36 inches), and the Start was 10 Mph. (3.0 sec. in 6 inches)

 

CV2= 55 at 5 Mph, CV6= 100 No. at 30 Mph, CV5= 192 No. at 60 Mph

        Scale         60 Mph         30 Mph        5.0 Mph      (Dist. in 6.00 sec.)

  N     1:160      40 Inches     20 Inches     3.3 Inches

 HO   1:87.1     73 Inches     36 Inches     6.0 Inches

  S     1:64         8.25 Feet     4.13 Feet      0.7 Feet

  O     1:22.5     23.5 Feet     11.7 Feet      2.0 Feet

Program the Decimal numbers from your plot into the DCC Loco. & recheck your Mph speeds. (A second try at a speed estimate probably won't be needed.) Some decoder don't support the three point speed Table CV2/6/5. If it is working, your locomotive will be running on the first step, and there will be a reduction in speed at full throttle. For more information on this subject see: "Using DCC to match locomotive speeds" M.R. Sept., 2006 page 76.

Regards,

Bob Frey

[Robert Frey]

Measured mph for the Plot is =  (60 or 30 or 5 mph) X (6 sec.) / (Stopwatch time)

If (stopwatch time)=  6.00 sec., then you are at the target mph! 

Scale Speed Calculator is a small utility that calculates scale miles per hour for the most commonly modeled scales by entering time and actual distance traveled. http://home.cogeco.ca/~trains/rrsoft.htm#cal      HO Scale: 73 inches in 6 sec, is 60.1 mph, 36 inches in 6 sec, is 29.7 mph, and 6.1 inches in 6 sec. is 5.0 mph.

TDP & Associates, Inc. Displays the scale speed of your train in MPH. This Electronic unit will report speeds of up to 150 MPH accurately. http://www.trainspeed.com/TrainSpeed1.htm

[Robert Frey]

If you would like to plot your HO Scale Mph on some graph paper, try the following:. Open your Word Processor to a blank page, set the left and right margins to 0.5 inches. Then, clink on pictures to enlarge. Copy pictures (Ctrl C), to your Word Processor, Paste Special (Picture), and then enlarge to 7.5 inches wide.

[Robert Frey]

For your three point speed Table CV2/6/5. if you think 5/30/60 Mph is good, then you will find that a target speed of: 4/24/64 Mph is even better. Most people make a low-belly speed curve. This provides finer speed-step control at the lower speed steps, for switching operations, and the V-Max. (CV5) has a little extra power to drive a train up a hill. The V-Start, V-Mid, and V-Max is a very easy way to produce a custom speed curve to a group of freight locomotives that can run together in one or more trains.  The following is an example: 

If CV2= 64 at 10 Mph,   CV6= 128 at 45 Mph, and   CV5=218 at 66 Mph

Then from plotting this data, the following estimates can be obtained.

CV2= 55 at 5 Mph,    CV6= 100 at 30 Mph and    CV5= 192 at 60 Mph

CV2= 53 at 4 Mph,    CV6 = 90 at 24 Mph and    CV5 = 209 at 64 Mph

For more information on V-Start, V-Mid, and V-Max subject visit:

http://www.loystoys.com/info/vstart.html

 

[Robert Frey]

Even if you don't use the three-point speed Table CV2/6/5, try a word search in Trains.com on just CV2. You will find other DCC users who have an interest in CV2 (Vstart). All DCC users can reprogram their CV1 (short locomotive address), but just by reprogramming CV2, your locomotive can start to move on the first speed step. This action also creates a low-belly speed curve. By doing this one change in the speed table, you can creates a finer speed control at the lower speed steps. The Vmid to Vmax speed steps can still be unchanged. (If CV2= 64 at 10 Mph & CV6= 128 at 45 Mph, then from plotting just one line you can estimate: CV2= 55 at 5 Mph)

For the names of Configuration Variables see Table 1a:

http://www.nmra.org/standards/DCC/standards_rps/rp922.html

In the NMRA Table 1a, note that CV2 (Vstart) is required, while CV5 (Vhigh) & CV6 (Vmid) are optional. So try CV2= 64. CV6= 128, & CV5= 218 in your DCC decoder, and you will quickly find out if the CV2 (Vstart) , & CV5 (Vmax) are both working. It may turn out that they only work in the 28-speed step mode.

[Robert Frey]

A Spreadsheet can estimate three point speed Table CV2/6/5 values at 5/30/60 or 4/24/64 Mph.

Cell C12=(D3-D4)/(C3-C4)  D12=0.5*(D3+D4)-0.5*(C3+C4)*C12  C13=D2-D3)/(C2-C3)  D13=0.5*(D2+D3)-0.5*(C2+C3)*C13        C5=C12*D5+D12    F5=C12*F5+D12        I7=C13*I5+D13     C6=C12*C6+D12     F6=C12*F6+D12     I8=C13*I6+D13         E7=6*12*88/A9     E8=6*12*44/A9      E9=6*12*7.333/A9    G7=(60/88)*A9*(E7/12)/C7       G8=(60/88)*A9*(E8/12)/C8    G9=(60/88)*A9*(E7/12)/C7   D2=G7      D3=G8     D4=G9

Example of a completed Excel spreadsheet File: CV2-6-5.xls at 4/24/64 Mph.

If you have an Excel program on your computer, then goto: http://bobfrey.auclair.com/ click on feedback. Request a copy of file: CV2-6-5.xls   The above formulas (put into their proper cells) can be used with any type of spreadsheet program.

[Robert Frey]

To find values for CV2/6/5 at speeds of 5/30/60, try the following. With a DCC locomotive, program CV2= 64, CV6= 128 and CV5= 218. Measure your Miles per hour scale speed at the first step (64), Mph at one-half throttle (128), and Mph at full throttle (218).

If you have EXCEL on you computer, a spreadsheet is available to measure scale speeds in Mph at Low, Mid., and High, with a stopwatch in any scale. By knowing the Mph speed when your throttle is actually set to Vstart = 64, Vmid.= 128 and Vmax.=218, it is possible to estimate the Decimal values for CV2/6/5 at the speeds of 5/30/60 Mph. (This could be considered a Speed Vs Motor Voltage plot, and be read at the 5/30/60 Mph points.) This spreadsheet is located in a file at: http://groups.yahoo.com/group/DCC4EVERYONE/ It is a friendly place, with a bunch of good people who are always willing to help out. There are no dumb DCC questions there. (If you are not a member you will need to sign in.)  File name is CV2-6-5.xls

[simon1966]

Bob, this is a very interesting set of posts and illustrates what can be achieved with the speed table.  There have been several discussions recently concerning speed matching and consisting so this will be helpful for those that want more detailed information.

[Robert Frey]

Speed matching different Mfg.

Data for CV2/6/5. --- Loco No: 1317. --- Decoder: Digitrax DH123. --- Mfg. Brass Import 1500 Switcher. --- Dec. at: 64, 128, 218, & 255 is 14, 35, 65, & 78 Mph. --- Then CV2/6/5 is 31/94/203 at 4/24/59 Mph. --- Remarks: CV5 with 10 cars is 4 Mph slower.

Data for CV2/6/5. --- Loco No. 1317B. --- Decoder: Digitrax DH123. --- Mfg. Athern 1500 B Unit. --- Dec. at: 64, 128, 218, & 255 is 2, 44, 90, & 110 Mph. --- Then CV2/6/5 is 68/95/174 at 5/25/62 Mph. --- Remarks: CV5 with 10 cars is 6 Mph slower.

Even with very different starting voltages and different maximum running speeds, these two DCC locomotives now run very close to the same speed. Even when uncoupled, through their entire speed range, they stay running close to each other.

[Robert Frey]

To try Spreadsheet CV2-6-5.xls visit:

http://groups.yahoo.com/group/DCC4EVERYONE/message/8634

Note: You will need to Sign in to Yahoo! to view message 8634

[SeadooChooChoo]

I've tried to get different locos to run together.  For example an Athearn SD70 (w/ a Digitrax decoder) with an Atlas Gold Series Dash 8-40C (w/ sound).  By adjusting CV2 & CV5, I can get the 2 to start together & run very well together throughout the entire throttle range w/o changing any other CVs.  I put them a car-length or two apart & run them around the layout & they stay pretty well spaced (I was satisified w/ it to this point).  However, when I added CV3 & CV4, the Athearn starts a lot later than the Atlas.  They start at about the same speed; the Atlas just starts several seconds before the Athearn.  If I turn the momentum down on the Athearn, they will start closer together, but the Athearn gets up to speed too fast for the Atlas.  So much of a difference that the Atlas will start spinning wheels when I couple them.  Again, they do pretty good w/o the momentum.  I'm trying to get a sound-equipped Atlas to run w/ each non-sound Athearn.  Do I need to use the charts above, or is there another CV that I need to be adjusting (What is forward/reverse trim & kick start?)  Any suggestions?

[Robert Frey]

I was pleased that by adjusting CV2 & CV5, you were able to get your Athearn (w/a Digitrax decoder) and a Atlas (w/ sound) to run very well together. (This was the purpose of speed Tabel CV2/6/5.)  When it comes to CV3 & 4, I like a long acceleration, and a quicker breaking rate.

http://www.atlasrr.com/pdf/HO_Train_Master_Sound.pdf    The FM Train Master Loco Manual Page 6. Selects the starting and stopping momentum for both. Level 0 (no load), Level 1-15, increasing load with acceleration to full speed from 5 seconds to 200 seconds. (CV3 = 15 is 200 Seconds, then CV3 = 2 is about 13 seconds, CV4 = 1 is 5 seconds.)

http://digitrax.com/ftp/decodermanual.pdf     6.4 Acceleration Rate: CV03 For example, a value of 01 programmed to CV03 will cause the decoder to change at 1/10 second per speed step (using the 28 speed step range). This means that it would take about 2.8 seconds for the loco to go from stopped to full speed if you command the loco to go immediately to full speed by cranking up the throttle. (Then CV3 = 5 is about 14 seconds, CV4 = 2 is 5.6 seconds.)

Notes from Digitrax TABLE V: The Kick Start CV65 provides for a short full voltage "kick" when you start the locomotive decoder from 0 speed. A value of 00 turns this option OFF. (This gives an extra kick to overcome friction & start the engine moving with say a high friction Athearn motor or and old open frame motor. CV = 20 is about 0.02 second full voltage type of start. Adjust this CV number to a "smooth running start".  A can type of motor generally does not need a "kick" start.)  For more info visit Kick Start: http://www.loystoys.com/info/kick-start.html

If you program Forward Trim (CV66) & Reverse Trim (CV95) to CV values of 128/x80, 000/x00, or 001/x01 you will get no scaling effect. A trim value of 255/xFF will give a 200% scaling of the table entry value. (These Trim values only work with the 28 step custom speed table. (Say your locomotive ran 10% faster in the Forward than in Reverse. Then CV95 = 128 + 12.8 = 141 for a 10% increase in speed for the Reverse Direction only.)  For more information visit: http://www.loystoys.com/info/forward-reverse-trim.html

For more information on CVs & mph Speeds see: "Locomotive Speed Control, Common CVs and Use", Model Railroader, June 2007, Page 77.

Regards,   Bob Frey

[Robert Frey]

Capitol City N-TraK, Speed Matching Locomotives (Calibrate you DCC Throttle to read scale Mph speed in N scale)

http://www.cuttergraphics.com/N-trak/speed_matching.htm

[Robert Frey]

If you would like to plot your Scale Mph on some graph paper, try the following:. Open your Word Processor to a blank page, set the left and right margins to 0.5 inches. Then, clink on pictures to enlarge. Copy pictures (Ctrl C), to your Word Processor, Paste Special (Picture), and then enlarge to 7.5 inches wide. Graph paper is Mph Vs Decimal Numbers to 255.

[topcopdoc]

I found this very interesting information. I am finishing up my HO layout and will start the operations part of it shortly. It will take some time to digest it all. Thanks alot.

Doc 

 

[Robert Frey]

Example of Graph Paper with Loco 1317B, HO

First, the factory defaults for any decoder is CV2= 0 , CV6= 0 and CV5= 0. The Start, Mid. and Max. three-point speed table are not turned on. Using info. from Loco. 1317B in HO Scale, turn you throttle full on. This example was, 3.27 sec. in 73 inches is 110 Mph. Draw a line from zero to 110 Mph at 255. Then, at 60 Mph CV5 is near 140.

Second, with the loco. programmed as CV5= 140, and CV6= 130 (assume mid. as 50%) and CV2= 65 (a very high starting of 25%). The Start, Mid. and Max. values are now turned ON. If the Loco. runs in the first step, then CV2 is working. If the Max. speed is reduced, then CV5 is working.

Third, Measure your actual speed. At CV5 = 140 is actually 52 Mph, at CV6 = 128 is actually 46 Mph at CV2 = 64 is actually 2 Mph. Then the new estimate for CV5 is 156 at 60 Mph, CV6 = 105 at 30 Mph and CV2 = 68 at 5 Mph.

Fourth, re-program your loco. and also, re-measure you speed to see if it is actually at the 5-30-60 Mph targets.

If you think that 5-30-60 Mph are good speed targets then you will find that 4-24-64 Mph are even better targets. This is because you will have a finer speed control on the lower half of your throttle.

[Robert Frey]

• 30 Mph= 30x5280 Ft./3600 sec.= 44 Ft.per sec.= 528 inches per sec.
• The following is a 30 Mph speed trap table, ran in 6.0 seconds.
• N:(1to160)=19.8"  HO:(1to87)=36.4"  S:(1to64)=49.5"  O:(1to48)=66.0"
•                      30 Mph Speed Trap Table
• Sec Mph      Sec Mph      Sec Mph      Sec Mph
• 1.5 120      2.6 69       4.2 43       8.0 23
•   - 116      2.7 67       4.4 41       8.3 22
• 1.6 113      2.8 64       4.6 39       8.7 21
•   - 109      2.9 62       4.8 38       9.0 20
• 1.7 106      3.0 60       5.0 36       9.5 19
•   - 103      3.1 58       5.2 35       10 18
• 1.8 100      3.2 56       5.4 33       11 16
•   - 97       3.3 55       5.7 31       12 15
• 1.9 95       3.4 53       6.0 30       13 14
•   - 92       3.5 51       6.3 28       14 13
• 2.0 90       3.6 50       6.7 27       15 12
• 2.1 86       3.7 49       7.0 26       18 10
• 2.2 82       3.8 47       7.3 25       20 9
• 2.3 78       3.9 46       7.7 24       24 8
• 2.4 75       4.0 45       8.0 23       30 6
• 2.5 72
• Calculator example: 180/Sec.= Mph or 180/4.8 Sec.= 37.5 Mph
•   
• The following is a 3 Mph speed trap, ran in 6.0 seconds.
• N:(1to160)=2",  HO:(1to87)=3.6",  S:(1to64)=5",  O:(1to48)=6.6"