Acceleration is the rate at which the decoder increases from one speed step to the next in response to a new command to increase speed.
CV03, acceleration, lets you simulate train weight or inertia. The range of values for acceleration is 000 to 031 (x00 to x1F hex). Setting CV03 to a value of 00 generates an immediate response to a new command to increase speed. As you increase the CV value programmed into CV03, the rate of speed step change is approximately 1/10 second per increment in acceleration value.
For example, a value of 01 programmed to CV03 will cause the decoder to change at 1/10 second per speed step (using the 28 speed step range). This means that it would take about 2.8 seconds for the loco to go from stopped to full speed if you command the loco to go immediately to full speed by cranking up the throttle.
Caution: If acceleration and/or deceleration are set at a high value, the loco may not appear to be working correctly. If your loco is not responding when you increase or decrease your throttle setting, reprogram these two CVs to 00 and try again.