View source for WOWSound Version 4 Indexed CV's

==Explanation of Indexed CV's==
"Indexed CV's" are a method which a decoder can use to store and change more configuration options than could be possible using the 256 [[NMRA Standard CV's|Standard CV's]]. TCS Non-sound decoders do not use Indexed CV's, since all of the configuration options can be squeezed into the Standard CV's. In WOWSound Version 4 and older decoders, TCS uses an indexed CV method which uses [[CV 201]], [[CV 202|202]], [[CV 203|203]], and [[CV 204|204]], which are described in detail below. All four of these CV's combined work as a method to "index" and manipulate the more complicated configuration options with many many possible options such as [[Mapping Sounds to Buttons]].
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==How to Use Indexed CV's==
Think of CV 201 through 204 as a filing cabinet. To make a change to a "file" in the "filing cabinet" you need to know the drawer and folder number where that file is. You also need to know what the info in that file is, or what you want it to be.

===CV 201===
CV 201 acts like the drawer - this is a "coarse" location of the information you want to edit. We use this to indicate the type of setting you would like to change. 

''For example, changes made to sound options and sound behaviour settings are in "drawer" number 4. Another example would be CV 201 = 6 for changing sound volumes.''

===CV 202===
CV 202 acts like the "folder" within the "drawer" (CV 201) in which the setting (or "file" in this analogy) lives. CV 202 indicates what specific type of change you would like to make. 

''For example, if CV 201 is 4, and CV 202 is 19, this indicates that you would like to reconfigure the "User Options" settings. Another example would be CV 201 = 1 and CV 202 = 5, which would map a sound to Button 5.'' 

===CV 203===
CV 203 is the "high byte" of the data/setting, and can vary in behaviour and usefulness depending on the situation. For some settings ("files"), the number of available options is less (0-255), meaning that this CV is not necessary and not used. In these cases, it should be set to 0. In some cases, any other random/erroneous value will not affect anything. 

In bit-wise CV's like the User Options, or settings with more than 256 available setpoints however, CV 203's value WILL affect said setting, and should always be verified to be correct and taken into account before proceeding. Neglecting CV203 in some circumstances will result in erroneous programming changes that may affect other settings you were not intending to change.

===CV 204===
CV 204 Is used as the final step in the process. Programming a value into this CV will use the information/data in CV203 and CV204 to make a change to the setting as indicated by CV201 and CV202. Only ''after'' programming CV 204 with a value will the changes you made actually take place. You can freely manipulate CV 201, 202, and 203 without any affect taking place until you program CV 204. <br />

==Reading Indexed CV's==
Note that all of the above steps are for ''writing'' to an indexed CV. In order to '''read''' the value from an Indexed CV, you need to follow these steps:

#Determine the "drawer" or primary index value, such as 4.
#'''Add''' a value of '''100''' to the primary index (CV 201). EG "4" = 104
#Set CV 202 to the secondary index location (same as described above).
#Program CV 204 to a value of 0, or any other bogus value. The value of CV 203 is irrelevant and can be skipped.  ''After writing any value to CV 204, the decoder will fetch the data from the index you selected (CV 201:CV 202), and place the value(s) into CV 203 and CV 204.''
#Immediately after writing to CV 204, you can ''read'' CV 204 and/or CV 203. CV 203 may not necessarily be in use, so it may return a 0, but CV 204 will always have some sort of data in it, including 0, which can be valid data.

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== Related ==

* [[WOWDiesel Version 4 Indexed CV's]]
* [[WOWSteam Version 4 Indexed CV's]]
* [[WOWElectric Version 2 Indexed CV's]]

[[Category:Technical Support]]
[[Category:Indexed CV]]