Hi,
I use the ESS and it is much preferred, much lower latency and electrical noise immunity.
Note that I use Mach4 and cannot be 100% about one-to-one correspondence to Mach3. The Mach3 plugin having been around
for so many years is in most respects more advanced and complete than the Mach4 plugin.
The ESS has an extra port, thus has more IO. In addition to the extra port it has a bigger FPGA. The bigger FPGA allows greater
support for different features.
The ESS plugin for Mach4 has:
homing, probing, slaving, backlash comp, lathe threading, PID spindle control but does not have THC as yet, we are told that its coming.
You would need to confirm with Warp9 TD but I believe all of these features are supported in the ESS Mach3 plugin AND THC.
The USS with the smaller FPGA does not have all these features. The Warp9 TD website makes it plain that the USS does not have
backlash comp or THC. The lack of THC support is due to the electrical interference of the plasma making a USB connection just too
unreliable.
I've used the ESS for 2-1/2 years and never had it run out of data, it is in short way WAY
WAY more reliable than the parallel port
it replaced.
I too have heard reports about 'run out of data errors' with not just the USS but the UC100, the 57U from Pokeys and others, ALL of them
USB connected. The Ethernet connection is very much more reliable. You may have noted that CNCDrive, the company responsible for the
UC********* products have discontinued their multiport (UC300 and UC400) USB models and are now making Ethernet connected boards only.
I'm OCD about wiring neatness, having an Ethernet smoothstepper would mean a hole drilled into the enclosure, and a wire hanging out of the hole so it could be plugged into the back of the motherboard.
Do you prefer wiring neatness or do you prefer a reliable, working CNC solution?
For example, if Mach 3 is sensing rpm via the index signal, and modulating the pwm pulsewidth to adjust RPM, does the smoothstepper not communicate these instructions to the breakout board, or does the smoothstepper somehow prevent these calculations from taking place at all?
I cannot be sure about the USS, my experience is with the ESS. It does read the index signal and does the speed calculation in real-time. What the SmoothStepper
cannot do, neither can any external motion controller hooked to a Windows PC, is update Mach in real-time. Windows is not a real-time system and the communication
delay make it worse. With Mach3 and USB you could be talking a 20-30 ms round trip from the controller to Mach and back again, its just too slow for a feedback
loop. The ESS enacts the spindle PID loop on the ESS board, all in real-time, it does not require intervention from Mach at all, Mach is the supervisor only.
Just as a matter of historical interest Machs parallel port is a near real-time control system, the parallel port driver lives in the kernel of the PC. The computing
world looked on in amazement when Art Fennerty produced the driver and achieved as good real-time performance as it does not withstanding its hiccups.
To my knowledge NO ONE has been able to duplicate Art's achievement. It was Art's driver that allowed a Windows PC to be a useful and cheap CNC control
and therefore Mach to become as popular as it has.
Craig
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