I have some MTH 2 rail engines running on DCC with Digitrax that I would like to program cv values for cv2,3,4, and 5. I’m wanting the engine to start off slow and pick up momentum. So far I haven’t found any information on where to start with values for theses cv’s. Anyone have values to get started with? Thank you
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2 is starting voltage - on a scale of 0-100. I would not bother messing with it at first If the MTH stuff requires higher voltage before it starts, you may need to do something here.
3 and 4 are acceleration and deceleration momentum respectively. The range is 0-255. I have never used more than 10. I would start and try 2-4 and see how you like it and then adjust from there.
5 is the maximum speed with a range of 0-255 with 255 being the max (ie no reduction) most decoders default to 255. Putting in numbers less than 255 reduce the top speed.
Another useful CV is 6. this is the midpoint of the speed range. Its default is 127 or half of max. I often set this to about 1/3 of my max to give more speed steps(control) on the slower half of the throttle control. For example if I set CV5 (max) at 200, I set CV6 (midpoint) at 65.
In my experience each loco tends to behave differently, other than identical models. So each one requires a little fidlling.
You can't really mess things up by experimenting a little, so don't worry about hitting an exact value on the first try. You might, but if not, it is easy to change.
Also, a lot of fellows recommend puting in starting momentum (CV3), but not much or any stopping (CV4). They assume the operator can control the stop gently by watching the loco. But most importantly, that allows a quick stop in an emergency. Whereas if you put in a lot of stopping momentum, the loco may keep rolling right into a parked string of cars or somthing when you try to stop.
Finally get out you instruction sheet and review the settings for CV29. CV29 controls 14/128 speed steps and also whether the loco runs analog or just DCC. It also allows you change which direction is forward. I have no idea what an MTH decoder has here that might include their control system or not. But again most fellows set CV 29 so the loco will not respond to straight DC (analog), and run only on DCC. The reason here is that sometimes when a short occurs or some weird signal on the track, some decoders where a loco is sitiing idle, decide that they are really running straight DC and take off like a scalded rabbit.
Also I have a Digitrax system also and I set the command station voltage switch to "HO" There are 3 settings on the toggle, N, HO, and O/G. this just increases the carrier voltage available on the track. I find the locos run plenty fast at the HO setting.
Thank you for the reply and MTH O scale 2 rail doesn’t support CV6. So I’ll try and work with CV3 and CV4. I have a DCS200 and have it set on O. I tried 20 in CV3 but there was no noticeable change.
Hmmm, that does not sound good. Since the range listed by NCE is 0-255, I would suggest try 100.
On the other hand, do you have an MTH manual that might define a different range and you are possible outside that range?
Try setting the command statin to HO too. That will give you better control, I think.
I guess if MTH does not support CV6, they are sort of compatible, but not compliant. In other words they implemented some of the DCC standards, but not all.
I have been searching the internet all day for some information as to a range to set, with no luck. I see there are technicians available with MTH Tue thru Thur, so hopefully I can talk them and get more information. Thank you
I have a list of factory default values for all MTH PS3.0 DCC CV's. CV2 is 16, CV3 is 0, CV4 is 0 and CV5 is 0. CV's 67-94 will allow you to really fine tune your locomotive's running characteristics as you can create your own speed table.
As I said, try experimenting a little. If 20 in CV3 does give much if an momemtum, try 100 or some such. then go the other way and try 5. All it takes is a couple of keystrokes and test run to see what happens.
Thank you CATNAP for the values and I’m assuming 67-94 is a 28 speed step, could I ask what values you started with? Also what did you do with CV29, if I read the manual correctly I need to enter 1 in CV52, 16 in CV29 and then the speed table I want in CV25, if I want to try one of MTH speed tables.