The best way to program the DCC decoder installed in Atlas N scale VO1000 locomotives depends on which DCC system you are using. With Lenz DCC systems, the VO1000 can be programmed in direct mode on the programming track, no matter which CV you are programming or which value you wish to program into this CV.

However, this decoder can be challenging to program with 4-digit addresses on certain other DCC systems. The VO1000 decoder requires more power on the programming track than these DCC systems can supply to read or program a CV (especially when the data value you are reading or programming is larger than decimal 126).

However, it is possible to program a 4-digit address into the VO1000 decoder by using Operations Mode Programming (programming on the main line). If your DCC system allows you to enter a 4-digit decimal address directly in Operations Mode, this is the simplest way to program the VO1000 decoder. I was able to use this technique with the NCE Power Pro DCC system, and I assume that it would also work with a Wangrow DCC system.

If you cannot enter 4-digit addresses directly in Operations Mode, it is necessary to calculate the values for CV17 and CV18 that will yield the desired 4-digit address using the procedure outlined below. Then use Operations Mode Programming to program the calculated values for CV17 and CV18 into these CVs. Once you have programmed CV17 and CV18, use Operations Mode Programming again to program CV29 with the value needed to activate this 4-digit address. (To activate a 4-digit address, add decimal 32 to the value for CV29 that is used with 2-digit addresses.) I was able to use this second Operations Mode Programming technique successfully with the Digitrax Zephyr DCC system.

Resetting the VO1000 decoder to its factory-default values is done by writing decimal “33” into Register 8 (CV8). Since the default value for Register 8 is 127 (Atlas’s manufacturer ID), it may not be possible to read the default value for Register 8 with your DCC system. Nonetheless, your decoder WILL be reset to its factory defaults if you first write decimal “33 into Register 8 (or CV8) on your programming track and then cycle the programming track power off and on (if your DCC system doesn’t do this power cycling for you).

Appendix: Relationship between CV17 & CV18 and a 4-Digit Address
The material in this Appendix applies to all NMRA-compliant DCC decoders, not just those sold by Atlas because the handling of CV17 and CV18 is part of RP922 of the NMRA.

Dividing the extended locomotive address into CV17&18
CV17 contains the higher-order Byte of the address. This Byte determines the range of addresses in which a particular 4-digit address will be located. If for example CV17 reads 192, the extended address can have values ranging from 0 to 255. If CV17 reads 193, the extended address can have values ranging from 256 to 511. This can be continued up to the value 231 in CV17, then the extended address can take over values ranging from 9984 to 10239. The table below contains a complete list of all possible ranges of addresses. Note that all numbers in this Appendix are stated in Decimal Format. (Some older Digitrax systems required the user to convert all numbers from decimal to hexadecimal format, although they did perform the calculations described in this Appendix for the user.)

Do not forget to set Bit 5 in CV29 if you want to operate a decoder with the extended address.

Calculating the higher and lower-order bytes (CV17 and CV18) that yield a specified 4-digit locomotive address:
First, decide what 4-digit address you would like to assign to your locomotive, e.g. you might choose the address “1234.” Now determine (from the “Table of Extended Locomotive Addresses" that is given on the next page of this Appendix) the "range of addresses" in which your desired locomotive address falls. In the column of this table to the right of the two columns that specify each range of locomotive addresses, you will find the decimal number that needs to be entered into CV17. In our example, the number to be entered into CV17 is “196.” To determine the value that needs to be entered for CV18, perform the following calculations:

Therefore, the number “210” is the value that needs to be entered into CV18. Your decoder has now been programmed to address 1234 (provided that you have also entered a binary “1” into bit 6 of CV29).

Calculating the 4-digit locomotive address that corresponds to specified values for CV17 and CV18
When reading out the address of a locomotive, first read CV17 and then read CV18. Then go through the steps described above in reverse order. For example, let us assume that you have read out the following: values for CV17 and CV18: CV17 = 228 and CV 18 = 145. First, look at the column in the table below that gives CV17 and so that you can determine the range of addresses that corresponds to this value of CV17. In our example, the first possible address in the range of addresses corresponding to CV17 = 228 is “9216.” Now all you have to do is to add the value of CV18 to this starting value for the address range and you will have found the decimal value of the 4-digit locomotive address that has been stored in CV17 and CV18.
The calculations to compute the 4-digit address corresponding to given values for CV17 and CV18 are shown below both for this second example and for the earlier example where the four digit locomotive address was 1234.