Your thoughts on the AR1200 from Machinery & Electrical

[JAZZCNC]

I have to ask JAZZ why he lumps low-spec and parallel port together. I know I only have a hobby machine from MD and I am vastly dissatisfied with it, but parallel port works OK within the (low) capabilities of my current machine - that is if the PCF07343 controller they used hadn't gone on the fritz. Is there some magic with usb motion controllers that makes something great happen ?

Well no one with any sense would go to the expense of buying a motion control card and running nasty cheap drives or Breakout board with them.! Equaly no one would buy servo's and run them with a parallel port at 25Khz.

The parallel port does work ok within reason. But when you get to wanting higher feed rates with higher resolution to give smoother motion then it starts to struggle. 25Khz just isn't fast enough and increasing the Kernal speed to gain extra pulses is increasing the chances for error and putting strain on the already much tweaked parallel port driver. This can lead to miss steps and allsorts of weird shit happenings.!!

I realise looking at the surface it appears Motion control cards are expensive luxury's but after you have experienced the difference you never will go back to the parallel port. The difference when matched to decent BOB and drives is night and day to parallel port, Motors run smoother, performance increases and missed steps etc when pushed hard become a thing of the past. PC and Mach's workload is greatly reduced as the Motion control card now does all the number crunching, this reduces chances of Mach3 locking up which is common when pushing the Kernal speed up and high feed rates.
Gone are the restrictions on which PC is suitable and how good the Paralle port is or needs to be.! Now you can use lower spec PC Even Laptops and run them thru a network if you like when using Ethernet(wouldn't advise it thou) Plus you can safely locate the PC and control further away from machine without worrying about cable length dropping signals.!
Usb motion control cards perform just as good but they still have some cable length restrictions and some can be affected by noise more(IE: Usb Smooth stepper)

So lower spec and parallel port do go together as you wouldn't go High spec on everything else and still run Parallel port. It would be like buying a ferrari and only using half it's gears.! . . . . . . Equally you wouldn't buy a ferrari Engine and put it in a low spec Lada and expect it to beat a Porche.!