I recently purchased purchased this Controller Box from Keling. It's very poorly assembled. Here are the problems I discovered:
1) The E-Stop button was wired up backwards, in a normally open configuration. Nothing would work until I pushed the button IN.
2) There is no connection of any kind to the GROUND tab on the AC power jack. Neither from the ground connector on the power supply or the case itself. If something shorts to the case it will make it live.
3) The DB9 connector provided for hooking up limit switches cannot be used as wired as none of the pins are wired to ground, terminal 12 on the G540 or -VDC on the power supply. All Keling did was to wire terminals 1 - 9 of the G540 to the pins, and not in any logical order. There is no documentation of any kind provided on the pin configuration either with the product or on the site.
4) The soldering job is very heavy handed and sloppy. There were a number of connections with little frayed wires coming dangerously close to cross circuiting the pins. No shrink wrap or other insulation was used to prevent accidental cross circuiting.
5) Most of the hardware connections (nuts and bolts) are only finger tight. The heavy power supply was so loose and floppy it almost fell out of the box when I opened it up.
Repeated emails to Keling for technical support yielded only half sentence responses which failed to answer my questions. Oh, the one complete sentence was "Contact firstname.lastname@example.org for the answer." Which I understand is a fairly typical response from Keling. At least Gecko was helpful in letting me know how to rewire so I could hook up limit switches.
It's all working fine now, but not without several hours of my own time troubleshooting and re-wireing. It's far from the "Plug and Use" as advertised on the Keling site. Also, it's obvious, with all these problems (especially the E-Stop mis-wiring) that the box was never tested with Mach 3 (as advertised) to see if it's functioning properly. If your considering purchasing this box, I'd strongly advise just buying the individual components and following one of the helpful schematics that can be found on the CNCzone.