The example 3 step speed tables in the Digitrax documentation are actually a good start. They have different ones for switchers and road locos. Switchers don't move very fast, so you would want to set CV5 to maybe 192 or less to limit the top speed. There's no point for a linear curve, so set CV6 to something less than half of that. ANd adjust CV2 so the loco starts moving on speed step 1.
A freight loco will vary depending on how big a train you pull, a linear curve (or just don;t set CV5 and CV6, just set CV2 so it starts on speed step 1) might be best.
A fast commuter loco will practically leap out of the terminal (well, if it was an FM Trainmaster it would) so you would set CV2 to start on speed step 1 and CV5 for some reasonable top speed, and then set CV6 to more than half the difference.
Think of it as a rope held on an angle. The low side is CV2, the high side is CV5. Now tie a string in the middle and pull it up or down to deform the curve - that's CV6. The steeper the slope, the more change there will be per speed step as you move the throttle. The more gentle the slope, the less change there will be per speed step.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Vail and Southwestern RR The reasonable values for any loco are the ones that make it perform the way you want it two. You could potentially have two "identical" locos, and have somewhat different values, compensating for differences in the motors, alignment, lubrication, etc. I don't think there's any one answer. For example, a reasonable value for the max speed is the value that has the loco running at the max speed you want it to. Remember, don't let the cart pull the horse here, you want to use the decoder as a tool, not as the end product.
The reasonable values for any loco are the ones that make it perform the way you want it two. You could potentially have two "identical" locos, and have somewhat different values, compensating for differences in the motors, alignment, lubrication, etc. I don't think there's any one answer.
For example, a reasonable value for the max speed is the value that has the loco running at the max speed you want it to. Remember, don't let the cart pull the horse here, you want to use the decoder as a tool, not as the end product.
ahhhhh, trial and error - this I AM well aquainted with!
Thanks, I appreciate the insight.
Jeff But it's a dry heat!
cacole Practically all decoders come with a factory default 28 speed step table that doesn't need to be changed. Check the decoder documentation. Unless you use Decoder Pro it would be extremely difficult to manually set a user speed table into the decoder. If you have Decoder Pro, you can set a speed curve very easily. The 3-step speed table is a linear table of 0 for speed step 1, 128 for speed step 2, and 255 for speed step 3. Adjusting this speed table is a quick solution if you don't necessarily want smooth transitions in speed.
Practically all decoders come with a factory default 28 speed step table that doesn't need to be changed. Check the decoder documentation. Unless you use Decoder Pro it would be extremely difficult to manually set a user speed table into the decoder. If you have Decoder Pro, you can set a speed curve very easily. The 3-step speed table is a linear table of 0 for speed step 1, 128 for speed step 2, and 255 for speed step 3. Adjusting this speed table is a quick solution if you don't necessarily want smooth transitions in speed.
I do have Decoder Pro, but have never played around with this facet of the program. I guess what my main concern is what might be considered "reasonable" values for a road switcher. For example what would be a reasonable value for the max speed? At about what speed step would the curve begin to transition from slow speed "switching" to higher speed "mainline" operation? I am assuming the table values would be nearly level for concentrated slow-speed performance, and turn upward only towards the end of the curve...I'm just looking for some input as to what others are using for curves. I'm new to this area, so please forgive my ignorance
Practically all decoders come with a factory default 28 speed step table that doesn't need to be changed. Check the decoder documentation. By NMRA DCC Standards, CVs 67 through 94 are the user uploadable 28 speed step table. You then have to set CV 29 to indicate that you want the decoder to use that table.
Unless you use Decoder Pro it would be extremely difficult to manually set a user speed table into the decoder. If you have Decoder Pro, you can set a speed curve very easily.
The 3-step speed table is a linear table of 0 for speed step 1, 128 for speed step 2, and 255 for speed step 3. Adjusting this speed table is a quick solution if you don't necessarily want smooth transitions in speed.
I have several models that are nearly "ready for primetime". Before they hit the track I would like to set up speed tables for realistic operation. The models are Atlas RS-36 (Trainman), ATLAS RS-11 (Classics and Yellow Boxes) and Athearn BB GP38-2. I model D&H if that makes any difference. The RS's all have DH165AO's installed, and the GP28-2 is equipped with a DH163d. I have seen the 3 step speed table on the Digitrax site, but would like something more precise. Would anyone care to share their speed tables for similar models, or direct me to a helpful website? I would like to set them up as "road switchers".
As always, Thanks for your help.