stepconf setup

Hello again. . . Andy, I saw a thread you responded to about stepconf and base periods and all that. I read all the manuals, hal and all that but I don't get what it means when they say to leave dirhold at 1 (the default). Usually it's at like 2000 or 20000 or something like that. I read this paragraph:

If we can use dirhold to meet the 20 us hold time requirement, then the next longest time is the 4.5 us high time. Add the 11 us
latency to the 4.5 us high time, and you get a minimum period of 15.5 us . When you try 15.5 us , you find that the computer
is sluggish, so you settle on 16 us . If we leave dirhold at 1 (the default), then the minimum time between step and direction is
the 16 us period minus the 11 us latency = 5 us , which is not enough. We need another 15 us . Since the period is 16 us , we
need one more period. So we change dirhold from 1 to 2. Now the minimum time from the end of the step pulse to the changing
direction pin is 5+16=21 us , and we don’t have to worry about the drive stepping the wrong direction because of latency.

over and over again and I just cannot understand it. Where did the 4.5 us high time come from? That was not mentioned earlier in the section.

Another question I have is about this paragraph that you write Andy:

strykerg wrote:
I thought the output steprate would have doubled whilst maintaining the same base period.
EMC2 can actually output a step every base thread, and the default stepconf configs set it up that way.
What happens is that EMC2 runs a module which resets a set of parport pins right at the end of the base thread functions.
However, it does this by waiting in a loop, which isn't ideal. Looking at your 'scope traces, in the normal step/dir trace the PC is effectively locked up during the ON phase (unless it is inverted).
You will probably find that at high step rates your base thread execution time is a lot lower with the quadrature output and system responsiveness should be better.
Quadrature is a much neater way to do things.

How do I know if my drivers can accept quadrature? I am going to be using KL-8070D. It says nothing in the manual about quadrature input.

I have been reading a lot about setting up the steps and base period and saw that you know your stuff about it, but I have a lot of unanswered questions despite searching the forums, that I am ceratain that you can answer. Like for instance, I would love to know the maximum speed I can jog my motors with my setup. I want to know what I should set my dirhold, etc. at with a keling setup. If I select keling drive, it sets it at like 20000 and 2000 or something like that. I want to know what all of these parameters mean. If I give you my whole entire setup, would you be able to tell me what to input?

This is the kit I bought: www.automationtechnologiesinc.com/produc...r-motor-3-axis-kit-5

I am installing it onto a grizzly x3. I purchased the ballscrew kit from Michael at cncfusion.com. I got the first kit at the top for $629. www.cncfusion.com/smallmill1.html

So that is my entire setup, what would you say?

I know I am asking a lot and I'm sorry, but perhaps it could help others as well with this same setup. I am desperate to know exactly what my settings should be. I have been studying this stuff for a couple of months and it's still very confusing to me.

Thanks for any help,

John

Did I do something wrong? Was it wrong to as a specific person on a new thread? I'm sorry if that is the case, I neglected to read all of the rules. But if anybody can answer, I'd appreciate it. Specifically about the quadrature input for those specific drivers. And how would I change to quadrature? And about dir setup and dir hold and all of that, why does that paragraph say that 1 is the default? As far as I can see, default would be 'other' and other is not 1.

Thanks,

John

Basic advice with step/dir:

Don't worry too much about direction setup and hold,
as long as these are longer than the minimum they will work
and making these larger has minimal effect on performance since these timings
are only used during reversals so seldom delay steps because the step rate
is so slow at reversal time.

Same with step space. Unless you are running a very fast thread,
its hard to violate this time on most step drives.

When the the stepgen is run in reset mode, the computer stalls for the step time so
if using reset mode, its best if the step time is not a large percentage of the total base thread period.

Very few drives support quadrature mode even though its better in every way than step/direction
so if your drive does not specifically have a setting for this, it does not support quadrature.

Pay attention to step polarity, its often not clear from driver/BOB specifications
what parallel port edge causes the actual step to occur, If this is wrong you may be
violating step time and dir setup / hold times without knowing it.
(inverting the step out polarity if nothing seems to work is a good test)

Also guys, what does this statement mean:

The greatest Pulse rate at max speed
determines the BASE_PERIOD.

?

I thought the BASE_PERIOD was determined via the driver specs, ie. dirhold, etc.? I have read this part over and over again and still cannot grasp it. ANY help is appreciated.

Thanks,

John

Thank you for responding PCW, you just helped me out a lot.

Where is step polarity, can that be changed in the pin setup in stepconf.?

I just want to learn about ALL of this. I am so interested in it and I love it. I think I like this part better than milling!

johnl2 wrote:

Also guys, what does this statement mean:

The greatest Pulse rate at max speed
determines the BASE_PERIOD.

?

I thought the BASE_PERIOD was determined via the driver specs, ie. dirhold, etc.? I have read this part over and over again and still cannot grasp it. ANY help is appreciated.

Thanks,

John

I think you have that backwards...

The highest pulse rate you can generate is determined by the base thread rate.
(maximum step rate = base thread rate)

The highest base thread rate you can use reliably depends on your computers latency.
Anormal rule of thumb is to set the base thread period to twice the computers latency figure.

As I said before, direction setup and hold timing are not really important here at all,
just set them long enough and they will be fine.

Step polarity can be changed with the "invert"
checkbox on the parallel port N page of stepconf.

So that statement is backwards? B/c I got that out of one of the manuals for linuxcnc. I thought it didn't make sense. . .

Thanks for getting back to me, you have been really helpful.

Let me know if it was me that was backwards or the statement I quoted from one of the manuals.

Thanks again,

John

Its definitely backwards.
If you can find where you saw that,
the manual can be fixed

It's in two places, same paragraph almost to the tee in two manuals. I will get you the url's and post them.

I have one more question if you don't mind. When I hook up my motor, www.automationtechnologiesinc.com/produc...tkl34h2120-60-4a-key, to my driver,www.automationtechnologiesinc.com/produc...eat-sink-is-included , in series, it goes so slow, it's not even workable. It works fine in parallel, but what could I be doing wrong? I should be able to run it in series, no? But if I turn up the acceleration or velocity, it does not even turn and acts very strange, like rumbling. Any help is appreciated and thanks again for all of your help so far.

John