*Set CV2, CV5 and CV6*

For this example, I am using CV2, 5, and 6 with a range of 0-255 which is the most common implementation of motor control. As always consult your manual for the details of your decoder.

These are defined by the NMRA as:

CV2 - Start Voltage

CV6 - Mid Voltage

CV5 - Top Voltage

It is important to note that not all manufacturers use CV 5 and 6 and there are a wide variety value ranges implemented by manufacturers.

For example, Soundtraxx does not use CV5 and 6 so you have to use a speed table to set the maximum voltage while MRC does not incorporate a speed table and uses a range of 0-32 for CV5 and 6.

Start by setting CV2 = 0 and adjust upward until the locomotive starts moving.

Next we need to set CV5.

We can guess at a value and tweak that until we measure 6V output across the orange and gray wires. Enter a value in the middle of the available range and start measuring...

We can also calculate the theoretical value of CV5 as follows:

CV5 = Target V / (Max V / CV5 Max)

Or, using the real numbers...

CV5 = 6V / (10V / 255) = 153

Or, stated another way...

Assume we measured 10V output at SS28 in the first step. Divide that by the maximum value of CV5, 255. Then divide the desired output voltage by this result to get the value of CV5, 153.