SoundTraxx SoundCar Technical Reference - Manual (Page 15)

Tsunami SoundCar Technical Reference Page 13
Primary CVs
Because CVs 17 and 18 are a paired CV, programming order is important.
Always write to CV 17 first, and then write to CV 18. The decoder will ignore
commands that attempt to program these registers out of order or with values
outside of the allowable range of 0xC000 to 0xE7FF.
These CVs may be changed in Service Mode at any time, but may only be
changed in Operations Mode if CV 29, bit 5, is cleared (i.e., CV 1, Primary
Address, is enabled).
Default Value: CV 17 = 192
CV 18 = 3 (Long Address 0003)
Related CVs: CV 1 (Primary Address)
CV 19 (Consist Address)
CV 29 (Configuration Register 1)