It has four independent drivers.
This is for use when you have (4) separate signals. It is targeted at the DSP, where the other interface board would have a lot of unused circuitry. It also gives you a terminal block, rather than a 'd' connector to simplify wiring. There will always be some amount of work because the rotary attachment needs to be removed. This board has a feature where you can remotely disable the motors while doing this.
The other application is a small CNC machine. The fourth axis driver could be replaced with a relay driver for spindle control.
The schematic is online now.http://www.buildlog.net/cnc_laser/erp/g ... ber=C32013