I tried multiple searches before posting this with no success. Surely I'm not the only one. I have a Powercab with two locos both with TCS decoders. K2D4 and CN to be exact. Both will default to 28 speed steps when I turn on the system. If I push the 28 / 128 button they both go to 128 speed steps until I turn off the system. Is there a way to make them or Powercab default to 128 speed steps? Not sure what sets the default. Thanks much; Charlie
Charlie, There are only two speed step architectures for decoders - 14- and 28-step. 28-step is the default for modern decoders and has been in common use since around '97, and there are 28 speed step CV's - CV67-94 inclusive. 128-step is an interpolated speed step range done within the DCC system. My PowerCab is always set for 128-step and when I disconnect then reconnect it's still at 128. When I change to 28 then cycle the system it remains at 28 until I change it back to 128. It toggles between the two when the 28/128 button is pressed. This is with v1.28C firmware. To test. if the fast increase/decrease button changes the speed steps by 10 then you are in 128-step or by 4 you are in 28-step.
I have firmware version 1.28a which may explain why yours does and mine does not. This may also explain why I got it so cheap last month. Thanks for the info Gary.
That is easy enough to take care of. Order a eprom upgrade from NCE. I and others did that about a year ago. There is also a very active Yahoo NCE DCC group that specializes in NCE products. Rich
That isn't quite right. While it is true that there is not a decoder setting for 128 speed steps, only a setting to distinguish between 14 and 28 speed steps, that doesn't mean the decoder does not operate in a 128 speed step mode. The 14 speed step command and the 28 speed step command look the same to the decoder, so if you are using one of them you have to let the deocder know which one you are using so that it will respond correctly. That is the purpose of the speed step setting in the deocder. The 128 speed step command looks completely different from the other commands so the decoder will automatically recognise it and doesn't need a setting to tell it to look for the 128 speed step command. The DCC system does not interpolate the speed steps, it simply sends the requested speed step to the decoder. Depending on the mode and speed steps, the decoder will often interpolate the speed steps. Some decoders will not let you use the 28 step table when operating in 128 step mode, so instead of interpolating from the 28 step table they just use a straight line conversion from the speed step to the speed. If the deocder is using the 28 step table and receiving 128 speed step commands, then it will interpolate the intermediate speed steps. Likewise, if the deocder is not using the 28 step table but has Vmid and Vmax set, then it will interpolate 14 and 28 step commands, and, depending on the decoder, either interpolate or use a straight line conversion for 128 steps.
No problems, Charlie. I would try the old 1.28a chip to check it myself but it's on the other side of the country in another PowerCab. But I do recall at one point needing to change the 14/28 speed step on power up at times. The 1.28c chip will allow you to use the USB Interface with a PC running software such as DecoderPro. Robert, thanks for pointing out my omission - it's what you get when rushing out the door. Of course the decoder needs to be able to understand the 128-step command.
