EddScott Posted February 26, 2011 Share Posted February 26, 2011 Does anyone know what the differences are between the Digitrax DS64 and the CML Electronics DAC20? The DS64 has 4 point decoders and DAC 20 8 point decoders, the DAC20 about £20 cheaper and seems to do just the same job as the DS64 - point detection and feedback over Loconet. With 60 points on my layout it will make a big difference to the cost! Link to post Share on other sites More sharing options...
RMweb Premium Steven B Posted February 27, 2011 RMweb Premium Share Posted February 27, 2011 I think you've outlined the key differences between the DS64 and DAC20 - the price per point controlled was what pushed me towards the DAC20. I've got a CML DAC20 and I'm very happy with it. There are ten feedback inputs on the board. That's enough for the points with two spare - I'm using the extras for reporting the state of IRDOTS. If you can live without the feedback functions of the DAC20 then have a look at the point decoders that MERG produce. They're much cheaper than the other alternatives. Happy modelling. Steven B. Link to post Share on other sites More sharing options...
DougN Posted February 28, 2011 Share Posted February 28, 2011 Eddscot, i have installed 5 No DS64's on my layout but as you have noticed the DAC20 is a cheaper option. I think next time I would go for the DAC20 due to less connections. It comes down to personal preference! Link to post Share on other sites More sharing options...
EddScott Posted February 28, 2011 Author Share Posted February 28, 2011 Thanks for the replies chaps! One small point - I presume that I have to use one decoder input per point - i.e. even with two apposing points I need one each? At the moment I have one switch per set of apposing points (using Masterswitch V2 at the moment) I've also had a little re-design of my layout and now need 3 single slips - I guess they use two point motors so would that be two decoder inputs used? Sorry if this is getting towards PC control - but that is the eventual aim Link to post Share on other sites More sharing options...
AndrewC Posted February 28, 2011 Share Posted February 28, 2011 What kind of point motors are you using? If they are standard Peco or SEEP, you should use 1 output per motor. If you are using the lower current Peco or a stall motor like Tortoise or Cobalt, you can put 2 of them on one output, crossovers for an example. Link to post Share on other sites More sharing options...
EddScott Posted February 28, 2011 Author Share Posted February 28, 2011 They are mostly SEEP with a few Peco motors. If there are two points on one decoder input, how does the point position feedback still work - is it just both points are assumed to be either facing or apposing each other? If the DAC20 can't fire two motors at the same time I could put the Masterswitch V2 in between which would provide the oomph. Link to post Share on other sites More sharing options...
Lady_Ava_Hay Posted February 28, 2011 Share Posted February 28, 2011 Thanks for the replies chaps! One small point - I presume that I have to use one decoder input per point - i.e. even with two apposing points I need one each? At the moment I have one switch per set of apposing points (using Masterswitch V2 at the moment) I've also had a little re-design of my layout and now need 3 single slips - I guess they use two point motors so would that be two decoder inputs used? Sorry if this is getting towards PC control - but that is the eventual aim I don't know the Masterswitch product but try investigating whether a single command from the accessory decoder will operate it. I suspect this is the case. You can link two Tortoise or Cobalt to a single output. If you have yet to invest in decoders and you wish to add point motors you might consider the Traintronics TT301 which has a decoder built in and numerous other features including one that Digitrax DS64 and DAC20 share which is push button operation i.e. a single push/on button will operate the point in either direction. The beauty of the Digitrax and CML decoders is that, if installed under the mimic board, you only need a two wire power connection to 12volts and a LocoNet cable. This is a huge saving on wiring. Route setting is common to all the products that I have mentioned Again I am not sure since I have not checked but you might ask whether the DAC20 is capable of accepting programming commands via LocoNet or whether it needs to be programmed on the programming track before install. The DS64 accepts programming on the LocoNet but still you need access to it as the change buttons are on the unit. Automated PC control will need DCC control of the points and the choice of point motor becomes more limited. Link to post Share on other sites More sharing options...
RMweb Premium Steven B Posted February 28, 2011 RMweb Premium Share Posted February 28, 2011 If you've got a Digitrax based system and a Loco-Buffer or other computer interface then you can use the CML software to configure the DAC20 so that one point will follow another - i.e. if you change one point of a cross over the second one follows automatically (with a delay if required). Another option if you've got point motors like the Tortoise or Cobolt is to use the set of DPDT switches on one of the motors to control the second point (and use it's switches as feedback into the DAC20). Happy modelling. Steven B. Link to post Share on other sites More sharing options...
AndrewC Posted February 28, 2011 Share Posted February 28, 2011 They are mostly SEEP with a few Peco motors. If there are two points on one decoder input, how does the point position feedback still work - is it just both points are assumed to be either facing or apposing each other? If the DAC20 can't fire two motors at the same time I could put the Masterswitch V2 in between which would provide the oomph. The feedback is based on opening and closing the common wire with the input. 1 point = 1 contact switch = 1 input for feedback. The danger here is if 1 point threw and the other stuck it makes the feedback meaningless as you only have 2 states. Thrown or Closed. There is no way of confirming that both points have moved on one output. Link to post Share on other sites More sharing options...
EddScott Posted February 28, 2011 Author Share Posted February 28, 2011 So how does feedback work on a point? I'm using SEEP PM1 with the switch contacts throwing the frog polarity (modded electrofrog points) On the DAC20 there are the 8 point decoder inputs and the 10 sensors which can be used for feedback - how is the point wired to the sensors to provide the feedback? Link to post Share on other sites More sharing options...
AndrewC Posted February 28, 2011 Share Posted February 28, 2011 So how does feedback work on a point? I'm using SEEP PM1 with the switch contacts throwing the frog polarity (modded electrofrog points) On the DAC20 there are the 8 point decoder inputs and the 10 sensors which can be used for feedback - how is the point wired to the sensors to provide the feedback? This is moving into the realm of product documentation. Short answer is pins 2-9 match switch 1-8. Pin 12 is the common. Connect pin 12 to pin 2 and the device reports that switch 1 is in the closed position. IF you are polarity switching you will need a second set of switch contacts to connect the appropriate sensor input pin to the common to indicate 'closed'. The pics in the manual explain it a lot better. Link to post Share on other sites More sharing options...
EddScott Posted February 28, 2011 Author Share Posted February 28, 2011 So, having read the functions of the DAC20 from the CML website, I think I'm OK. The DAC20 can also report the position of points from the stored state WITHOUT needing feedback microswitches attached to tiebars Thats my question answered I think? Link to post Share on other sites More sharing options...
Lady_Ava_Hay Posted February 28, 2011 Share Posted February 28, 2011 So, having read the functions of the DAC20 from the CML website, I think I'm OK. The DS64 offers this too. Link to post Share on other sites More sharing options...
DougN Posted March 1, 2011 Share Posted March 1, 2011 Sorry a little one on the DS64 it can cope with 2no Peco standard motors... the instructions even say so! On the one out put. I have 2 cross overs which I am planning to put on single outputs to the decoders Link to post Share on other sites More sharing options...
EddScott Posted March 1, 2011 Author Share Posted March 1, 2011 Sent a quick email the CML to ask whether the DAC20 will throw 2 solenoid motors - also to ask if the transformer I'm currently using will be too much - its a hefty 18V 8A supply and gives pairs of SEEP PM1s one heck of a wallop. I've greased all my PM1s with radio control car diff grease and the difference was very noticeable. Fitting PM1s is the bane of my railway modelling! The reply was that it will probably throw two at the same time but might not be completely reliable. I'll go with the DAC20 first and see how it copes. Link to post Share on other sites More sharing options...
AndrewC Posted March 1, 2011 Share Posted March 1, 2011 Ed, getting back to the feedback issue. The DAC and DS without feedback will only report what they think they've done. If you are trying to push 2 motors at once and they don't go over all the way the DAC will report 'thrown' while the feedback will still report 'closed'. Even though its extra wiring I tended to use feedback because I use routes and if a route setting doesn't go over completely the feedback to JMRI forces the correction once it sees the sticky point hadn't been thrown. Link to post Share on other sites More sharing options...
EddScott Posted March 1, 2011 Author Share Posted March 1, 2011 I know however I'm not sure how to provide another set of contacts to my points. I'ved used the PM1 switch contacts for frog polarity. I modded all my points to make them more reliable and didn't intend to have PC control at first. Link to post Share on other sites More sharing options...
locoworks Posted March 2, 2011 Share Posted March 2, 2011 Ed, getting back to the feedback issue. The DAC and DS without feedback will only report what they think they've done. If you are trying to push 2 motors at once and they don't go over all the way the DAC will report 'thrown' while the feedback will still report 'closed'. Even though its extra wiring I tended to use feedback because I use routes and if a route setting doesn't go over completely the feedback to JMRI forces the correction once it sees the sticky point hadn't been thrown. could the feedback part be ran through both point motors instead of just one so if either point failed to actually move then it wouldn't show anything? so it can show closed or thrown on a track plan and if it shows nothing one of the points hasn't moved? Link to post Share on other sites More sharing options...
EddScott Posted March 3, 2011 Author Share Posted March 3, 2011 I assume you would need independent feedback from each point so that if one point didn't throw properly it would either try again or give some sort of warning. The DS64 and DAC20 from what I gather "remember" which state the points are in so report the feedback in that manner - they are basically guessing. So again, I'm assuming, that if you had two points on the same decoder output, you would either get an open or closed report for both points. My question then would be how would the chosen PC control software cope with that? On the mimic panel on screen you have two points facing each other - so would the software need addresses for both points? Could you have the two points facing each other on one address and the software show both points thrown on the mimic panel? Link to post Share on other sites More sharing options...
RMweb Premium Steven B Posted March 3, 2011 RMweb Premium Share Posted March 3, 2011 The DCC system only "remembers" the state of the points if you don't have the feedback inputs connected. With the switched on the points connected to the feedback inputs on the DAC20 the system knows the state of the points when the system powers up. Any points that don't have feedback rely on the last DCC point controll message and so may be inaccurate. The problem with controlling two points from one output is detecting if both points on a crossover have thrown correctly. It's possible to connect point switches so that you can detect if they're both thrown. It's less easy to get correct indication that one or other of them hasn't thrown. With a cross over there are four states thrown-thrown, thrown-clear, clear-thrown and clear-clear. Typically feedback inputs only give you one. Happy modelling. Steven B. Link to post Share on other sites More sharing options...
locoworks Posted March 3, 2011 Share Posted March 3, 2011 it doesn't really matter which point hasn't thrown correctly as regards feedback if they are both on the same accessory decoder output, you just send the command again and hope this time the one that hasn't moved pulls its finger out. where it may be useful to know which has let you down is if they are on seperate outputs and some sort of route setting has been used. Link to post Share on other sites More sharing options...
RMweb Premium Steven B Posted March 4, 2011 RMweb Premium Share Posted March 4, 2011 it doesn't really matter which point hasn't thrown correctly as regards feedback if they are both on the same accessory decoder output, you just send the command again and hope this time the one that hasn't moved pulls its finger out. where it may be useful to know which has let you down is if they are on seperate outputs and some sort of route setting has been used. If you use swtich contacts on one point motor to provide feedback you only know if that one point has thrown. You could route the feedback through two sets of switches but then you'd only know if both points were set in one direction. You could tell that both points were set as thrown but it would not be possible to determin if they were both set clear or if one set thrown whilst the other set clear. To confirm that both points are correctly set you'll need to use two inputs. Fortunatly the DAC20 has two additional inputs which means that you should be able to switch two points from one output whilst having feedback from both points. Happy modelling. Steven B. Link to post Share on other sites More sharing options...
Butler Henderson Posted June 6, 2015 Share Posted June 6, 2015 Anyone managed to get a ninth or tenth point to work with the Dac 20s route setting. Can get all 8 point motors wired to route set but not the ninth driven by Digitrax decoder. Link to post Share on other sites More sharing options...
Butler Henderson Posted June 9, 2015 Share Posted June 9, 2015 Turns out the additional points that the route setting can work is only available to Loconet dcc systems. Link to post Share on other sites More sharing options...
bgman Posted June 9, 2015 Share Posted June 9, 2015 Not sure if this is relevant but has anyone seen these products http://loolee.org/megapoints/prod_mp.html May be worth considering for anyone wishing to set routes etc There are some really good videos to show the products and having spoken with the owner this week I like his attitude towards the hobby. He's a railway modeller who wanted to make life easier and has now started to produce these items for general sale. He also told me that if anyone wishes to send a plan/diagram he will happily advise on the best products. Usual disclaimer etc. Link to post Share on other sites More sharing options...
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