Model Railway Forum

I have a bit of software (bespoke) that times a loco over a known distance between two sensors (reed switches) and calculates the speed in scale MPH. This is useful as different locos run at different speeds on the same speed steps, so to get reliable automatic train operations I need to have a speed steps vs MPH cheat sheet for all my locos.
E.g. to get to 60MPH I have to set my DMU to speed step 80, but my RNFE 321 only needs speed step 50.

Thanks to all of you for your comments. Great to know that there are people out there who respond so quickly and positively to questions from people like me who are, even after a couple of years, still trying to get to grips with DCC.
I have managed to successfully insert chips into five Lima locomotives and am very pleased with the results. But the last two I tried were abject failures. One was a Lima 125 loco. It worked perfectly on DC as did all of the others. Inserting a Rails of Sheffield decoder seemed to work well but when I wanted to stop the locomotive from full speed, it ran with no change of speed at all for about five seconds, then gradually slowed to about half speed and then violently ground to a halt. Altering CVs had no effect at all. The decoder has since been tested by a DCC Concepts rep who could find no fault with the chip. A Gaugemaster chip fared no better. So, not all Lima pancakes work the same!
Thanks again!
ElectronicVin

Have you set CV4 Deceleration rate to 0 or 1 depending on decoder? This is deacceleration Off.
Is the loco and its decoder seeing the rail volts as DC? In which case turn off DC operation via CV29. So read CV29 value and add 4 if 2 or reduce to 2 if it reads 6. If long address is used read CV29 value and either reduce value by 4 if 36 or add 4 if reads as 32. Use this CV value chart to set the correct value http://www.2mm.org.uk/articles/cv29%20calculator.htm
Finally, assuming you have a DCC power Bus pair feeding the rails, consider fitting Bus Filters to the ends of the Power Bus.