Cv 66 forward trim – SoundTraxx DSD-150/DSX Technical Reference User Manual

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Digital Sound Decoder Technical Reference

CV 66
FORWARD TRIM

Description
Contains a value, n, between 0 and 255 that specifies a scaling factor interpreted as
N/128 by which the forward drive voltage is multiplied.

bit 7

bit 0

D0-D7: Forward Trim Scalar

The forward trim scalar allows the decoder’s overall throttle response in the forward direction to
be adjusted up or down for the purpose of matching one locomotive’s speed curve to another.
See graph below.

A trim value of 128 (0x80) yields a scaling factor of 1.0 which will have no net effect on the speed
response.

Trim values between 129 and 255 (0x81-0xFF) have the effect of increasing the motor voltage by
a factor ranging between 1.01 to 1.99.

Trim values between 1 and 127 (0x01-0x7F) will decrease the motor voltage by a factor between
0.008 and 0.99.

A trim value of 0 disables the trim scalar
computation.

This CV is used only when speed tables are
enabled (CV 29, Bit 4 = 1). Otherwise, this
CV will have no effect.

Default Value:

128 (0x80)

Related CVs: