The DAC20 points are controlled by DCC accessory messages. It responds to messages for its base address through to (base address + 7). when it "sees" a message for it, the green LED flickers off twice.
There are lots of possible reasons why your points may not be operating as expected. This guide helps to resolve possible problems.
The DAC20 have ten external inputs on SK3 for switch or sensor feedback purposes: 1-8, A and B. These inputs can be configured to create LocoNet sensor messages so that information is available to other devices on LocoNet. the popular "IRDOT" optical sensors can be used. This works with both the IRDOT1 and the IRDOT2: the relay contact isn't needed for this.
The DAC20 can be powered from a +14v to +18v supply instead of from track power. The advantage of doing this is simple: if there is a track short caused by a derailed train, you still have power to operate your accessory devices. The only downside: routes in a DCS100 command station can't be used.
Peco make a good 3 way point which allows good use to be made of limited space. These points work well, but have two sets of tiebars which must not be driven into each other - or a track short occurs. The DAC20 can avoid that; here's how:
The DAC20 will control Peco motors and work with a Digitrax command station. You will need a DC power feed of approx 18v to boost the voltage that operates the motors.
It is very easy to program: at a minimum press a button on the DAC20, the set the first point with your throttle and the DAC20 will memorise that address. That's probably all you need to do to get started.
The ECOS is a powerful command station. Among other things it can generate rail packets that are for non DCC systems. However, the DAC20 cannot decode some of these.
You CANNOT connect a DAC20 to the track output of an "Intellibox" controller. It has a different kind of track output from Digitrax systems.
While the DTM30 and the DAC20 work well together. It is necessary to program the DAC20 so that it generates the right LocoNet messages when the railway starts up, so that the DTM30 LEDs light up.
LocoNet allows the DAC20 to report information to other devices. It can be used to generate sensor messages (for example to report track occupancy) or it can report the current position of the points it drives.