Help needed on Tawcrafts DCC Point Controller

[Simon G]

My MRC has been left a couple of Tawcrafts DCC Point Controllers by a deceased member.  They come with a single page of instructions, which are helpful in themselves, but do not address the issue of the base address and how to change it.  I am familiar with loco decoders, but not with accessory decoders, so it is all rather new to me.  I am trying to find out what is the base address (presumably in CV1) and how to change it.  I have read that some accessory decoders have an on-board switch to put them into programming mode, but these dont seem to have one.

 

The units seem well made and with 2 4700 microfarad capacitors, will presumably throw multiple points with ease.

 

Picture of the decoder and one of the instruction file attached.  I have tried the email address and mobile number shown, but both now do seem to exist!  Any help gratefully received!

 

Thanks, Simon

 

[bandmbill]

 

My guess, based on older accessory decoders from a few years back, would be that you attach it to a DCC programming track and write to CV1 the base address in the same way you would change the address of a loco.   Once programmed then connect to the normal DCC output of your system.

 

If you program it to address 20 then output 1 would be on address 20, output 2 on 21, output 3 on 22 and output 4 on 23...

[Nigelcliffe]

I'm unsure on addressing. 

 

It might use "blocks of four" addresses.  Thus, CV1=1, means the outputs are 1,2,3,4,  but CV1=2 would be outputs 5,6,7,8,  and thus CV1=20 would result in addresses 77,78,79,80.  

 

And regardless of which addressing scheme, there's "how does your DCC system maker interpret accessory addresses",  so a value of 1 in CV1, might result in outputs being accessory addresses 1,2,3,4,  or they might be 5,6,7,8.    If applicable, the shift will always be +4.     (There's an ambiguity in the DCC standards). 

 

 

The use of CV9 is non-standard, and with no other information to go on, its more guesswork.  
 

[bandmbill]

14 minutes ago, Nigelcliffe said:

I'm unsure on addressing. 

 

It might use "blocks of four" addresses.  Thus, CV1=1, means the outputs are 1,2,3,4,  but CV1=2 would be outputs 5,6,7,8,  and thus CV1=20 would result in addresses 77,78,79,80.  

 

And regardless of which addressing scheme, there's "how does your DCC system maker interpret accessory addresses",  so a value of 1 in CV1, might result in outputs being accessory addresses 1,2,3,4,  or they might be 5,6,7,8.    If applicable, the shift will always be +4.     (There's an ambiguity in the DCC standards). 

 

 

The use of CV9 is non-standard, and with no other information to go on, its more guesswork.  
 

Yes - might be setting blocks…..  I built 4 MERG Accessory Decoders 20 years ago - they were programmed on the programming track but I can’t remember how the addresses were set - they did work really well though….

[bandmbill]

Probably just do some tests program to an address then test with point motors attached…..

 

Looks like you can’t adjust anything apart from address - if the units work with your point motors of choice then maybe find more modern units?

[John Clitsome]

Look v similar to Gaugemaster Dcc30 ACC Decoders. Have a look at the instruction sheet online - it might give a clue.

[Simon G]

Thanks for all the help and suggestions - issue now sorted!  I first tried connecting one of the units to my Powercab, but couldnt read any CVs, so I then connected the required DC voltage as well and found that I could read the CVs.  CV1 read as 2, but didnt work on accessory address 2, so I tried 5 as per Nigel’s suggestion that it might be a block system.  That worked perfectly with a Peco solenoid point, and accessory address 6 worked with the next output etc.

 

Sadly, the second unit hasn’t responded to being powered up, as the power LED doesnt light and I cant read the CVs, so something in the unit has failed.  At least one of out of two is better than none!

 

Thanks again for all the help.