CV Value Curiosity

[doublepeg]

I have started reading CV's through my Railmaster rather than my Elite, this gives two values, the value I programmed in and Status/String, e.g. I programmed CV3 to 75, in the Status/String column is the value 99 20 3 75 63. To satisfy my curiosity what

 

is this please?

[poliss]

Complete guess, (since most of my DCC links no longer work), something to do wit Hex or Decimal values, although I expect someone does actually know.

[Gregd99]

I had a look at the xpressnet specification and the data that is being displayed is the response from the elite to the request for the loco CV value.

 

The way xpressnet (the protocol on the usb link between pc and elite) works is that it sends a

 

request message to the elite. the elite then does whatever has been requested and sends a response.

 

The response that has been sent is as below:-

 

Service Mode response for Direct CV mode

- header = 90 (decimal)

- data byte 1 = 20 (fixed)

-

 

data byte 2 = 3 (CV requested)

- data byte 3 = 75 (value of CV requested)

- XOR byte = 63 (a check byte to detect errors in transmission)

 

so in English..... the numbers are just saying that you read CV 3 and got the value 75.

 

I am a little

 

bit surprised that this info is there. it looks like debug stuff to help the programmers.

 

 

[Gregd99]

ps..... if you are interested the xpressnet spec is available at http://www.lenzusa.com/1newsite1/Manuals/xpressnet.pdf

 

the elite USB interface more or less.... a little less than more... follows this spec.

[doublepeg]

Thanks for the replies fella's,

 

I guess it's nothing to concern myself with, it looks like one for the boffins!