My last post was in response to this statement:
in fact convert to serial, and this can cause slow speed.
in ARM processor ,This feature is embedded in the controller, and this is their strength
When I sent the post you had already posted simpson36, when I tried to modify my response with the text so denoted below I found the forum was down for a few minutes. My response to Amir was relevant to his comments.
As to your question about latency is an issue with any form of communication. Inside the PC much of the communication is synchronous, the signals are sent and received in time with a shared clock (there are different clock sources for different things.) With the parallel port driver the latency between when the driver should be called by the OS and when it actually is called is the issue. With an external motion control device operating over USB or Ethernet, which are both synchronous forms of communication (no shared clock), latency comes from the nature of the communication system itself and is much more variable. External motion controls have built in hardware to generate the step/direction signals and respond to time critical things like limit switches or probing. Since the time critical stuff is done in dedicated hardware you get better performance, but anything requiring a 'real time' interaction with the PC will have a split second lag.
This section is what I tried to post before:
simpson36, I'm never looking for a fight.
I was trying to use an emoticon
to show that. I guess I must come across much differently than I intend to. You said you did not know much about the SmoothStepper and made an incorrect assumption and I tried to point out the irony whilst correcting misinformation. It was not meant to be offensive, sorry it made you feel otherwise.
My last post was in response to this:
Your original post made assumptions that were just not factual, such as the SmoothStepper not being a 'real' USB device. That is like saying device that uses a RS232 to TTL level translator chip is not a real RS232 serial device. Most Ethernet devices use an external Ethernet chip, does that not make them real? My point was that the functionality of a bus translator is the same no matter if it is built into a uC or a separate device. It dose not make it any more or less real or lead to any loss of speed or functionality.
There is some of the parallel port functionality that the SS does not yet emulate, and as you said I've been one of the first one to mention that fact. I also sell them as you say but I try to cover the benefits and drawbacks of all the items I purvey; I like folks to be able to make an informed decision. I do not appreciate the personal insult against my character by you suggesting otherwise, that is uncalled for. I spend a great deal of my time trying to help other folks on forums, in email and by phone, and I don't get a dime for it 99.9% of the time. I do it because I like to help other folks have a good time learning about CNC.
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