Smooth Stepper:website:
http://www.warp9td.com/Two variants, USB (USBSS / USS) or Ethernet (ESS)
Product Comparison here:
http://www.warp9td.com/index.php/products/#detailsNote the rest of this is biased as I am a user of the ESS and active on the forum.
In short, ESS = 3 x LPT ports, USB = 2 LPT ports + a differential port (which can also be used as inputs).
Both have an expansion port.... which has not really been developed publicly since they were both launched / sold, there is an aspiration to provide an SDK, but that is my opinion only.
There is a lot on information on the official website. The PDF manuals are some years old, but still relevant, and
The ESS has a more developed driver for Mach3 than the USBSS.
The ESS has backlash compensation, THC and M10Px/M11Px support, the USB does not.
Because both are FPGA they are reliant upon the plugin to provide the functionality, and both have good potential for really good development, but the development cycle is unfortunately slow (updates of plugins tend to be on about a yearly (roughly) if you have a look at the plugin release dates on the website).
I bought a USBSS but did not use it for years (made the usual mistake of buying the moving bits before building the machine....), when I came to use it I struggled with the ground loop issue that the USBSS is known for, and at that time the website was not very informative, it has improved drastically over the last year, then I found out that Torch Height Control (THC) was not available via the plugin and backlash compensation and I re-evaluated.... Ethernet SS or something else... after much deliberation settled on the ESS because of the ethernet connectivity (better noise immunity, longer transmission distance), M4 plugin being developed (or at least an official statement to that effect at the time), CS-Labs CISMO came close.... but cost was higher (although it does not need a breakout board..... in hindsight I probably should have gone with that probably because of things like threading which I may want to add to my lathe later, and i've probably spent as much on breakout boards (but there are cheaper ways to provide easy to wire terminals via LPT BOB and DB25 <> IDE 26 ribbon cable that what I did).
SS has a lot of potential, but is reliant upon the developer (as most motion controllers are especially if you want more than one LPT port equivalent) ..... Pokeys has some good potential but it may not have enough IOs for your too.
Third choice came the PureLogic PLCM-E3 but it was about the time that Russia annexed Crimea, and there were some restrictions starting from the EU, their products seem to have since disappeared from ebay and one of their suppliers in the UK so I suspect that their products are being restricted by the current political climate.... but still a good product but only Mach3 support (at present) and it requires their own addon module for torch height control (extra cost from them). Comments on the forum of their products has been good and any issues identified have been sorted very quickly (which has not been the case with some motion controller developers).
You asked two questions on the ESS:
>>SSE -how many I/Os totally it has?
Answered above.... 3 x LPT equivalent ports, with ports 2 and 3 configurable as all inputs or standard LPT type I/O arrangement. (forget about the "expansion port" as its not available unless you set about to programme the FPGA from scratch).
>>Is the version for bi-polar stepper motor of it available in market?
Not sure if I am understanding this question... the ESS provides step and direction signals to 6 axis (+ spindle) stepper motor divers and the stepper motor drivers must control the stepper motors (serial or parallel wiring configured).
The ESS seems to be by far the fastest motion controller on the market as to how fast it can driver stepper motors.... although I'm not aware of anyone actually being able to use it that fast...(up to 4mHz!)... I'd be surprised if you were stepping a stepper drive over 100kHz (maybe servo drives.... never used them).
If you are interested in the SS, have a look at the website, and register and log on to the forum to check out the issues, as some elements (threading) have been an issue for some users for years, and also the common user issues are discussed (ground loops, look ahead, axis step rate / frequency, and velocity update frequency). Would hate for you to become someone waiting for something to be developed or sorted out that you did not know about up front.
If you have a basic milling machine or lathe or plasma or laser the ESS will more than likely meet your needs driving up to 6 stepper motors, on a windows PC with Mach3. Potential for Mach4 is there with the initial driver release, and another one due soon (been imminent for a while now) ... but then there may be a timeout as they want to develop the USBSS plugin for M4, and then maybe other bits before catching up with ESS development on M4.