Exactly what are “configuration bits,” and all the caution about adjusting them? As I read about it, it seems a single CV is used to store related on/off toggles in several binary 1 or 0 values. The value of these binaries is expressed as a base 10 number. That number will be represented by a unique combination of binary numbers. For example, CV29 in one of my locos has a value of 34. That means that the binaries for 32 and 2 are “on” (value of 1).That would be bit 5 and bit 1. The bit numbers start at zero. So, at eight bits (bits 0 to 7) needed to span values from zero to 255, that value of 34 would look like: 00100010 If I need to change bit 3 to one for using the 28-step speed setup, it will look in binary like: 00101010 That bit 3 is the binary expression of eight, so 34 + 8 = 42, So the value I enter for CV29 to change only that bit, would be 42, right? This seems reasonably straightforward, but all the caution in decoder users guides is unaccompanied by actual instruction or explanation of how to do it, or how it works, so it leaves the user on their own. But anyway, am I right on this?
Have you seen the CV29 calculators that are on the internet? For me that is the easy way to go. Here is one and there are more... https://www.digitrax.com/support/cv/calculators/ Sumner
Thanks. That is helpful. Binary math, like I thought, but I did have the wrong bit for 28-point speed table control.
Your understanding of CV29 is correct. I think a lot of the caution is because several of the features controlled by CV29 are tied to other CVs that you have to adjust in tandem. For example, if you enable 4-digit addressing by turning on bit 5 in CV29 (i.e. adding 32) without also programming the 4-digit address bytes into CVs 17 and 18, the decoder can become non-responsive to any address. At that point a reset will fix things, but at the expense of resetting any other CVs you've already adjusted.
So, then, if you program the decoder for long addresses first thing and give it one, in addition to the programming device feeding the address into CVs 17 and 18, it would also be feeding bit 5 of CV29, then, right?
I can only speak for Digitrax systems, but with them when you program a 4-digit address it does automatically overwrite CVs 17, 18, and 29. I've only had to manually adjust CV 17 and 18 a handful of times (out of dozens or hundreds of address changes) with off-brand decoders that didn't register all 3 CV changes for some reason.
This has been a very informative thread for me; many extra little things learned. I don’t have a laptop to hook to the train layout, and my desktop won’t get clearance to be relegated to the bonus room, where the layout is. A laptop, maybe someday.
It will run on about anything. I'll bet you could find a used laptop for under $25 at a yard sale, thrift store or ???? DecoderPro makes programming very easy. Can't imagine not having it. Do you have a DCC system? If so which one? If not you can get into DCC with DCC-EX for well under $100 (get parts from China and probably under $30. Don't let the low cost fool you it can do about anything the commercial units can do and more in some areas. Sounds like with your interest in how things work it might be a perfect system for you. Sumner
If you're not comfortable assembling your own DCC++EX setup, a SPROG II and a small/portable test track near your desktop, even if only temporary, would allow you to use JMRI for programming your decoders. But speed-matching locos would need a larger test loop, or your layout. BB has new, non-open-box 11" Windows laptops for $110. You might find a deal on a used laptop or desktop at a PC repair shop too. You only need internet access to install/update JMRI*, not to run JMRI. You would also need a USB interface for your command station, unless it has one built-in (DCC++EX, Digitrax DS-52, SPROG, et al.) *You could download the JMRI installer to a USB stick from a computer that has internet access, then transfer the stick to the computer on which you wish to install JMRI.
