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Re: input read frequency?
« Reply #10 on: May 08, 2010, 02:01:21 PM »
I use the index for read the velocity of my motor spindle, have ten groove in the axis and the motor rotate until 3000rpm, then the input frecuency is of 500hz and this is read correct. In my case I would ask the foreros what precision obtained when using the HOME of the match?. I use the HOME with my drivers and the Z of the encoder and is precise.

regards
Renato
Re: input read frequency?
« Reply #11 on: May 08, 2010, 02:52:37 PM »
foreros is forum,,

Offline BR549

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Re: input read frequency?
« Reply #12 on: May 08, 2010, 03:20:24 PM »
HI Ian the mill itself repeats to .0001-4 depending on the time of day and  the probe repeats to .0002-5.

Anything smaller than this I can't measure acurately here.

NOW ARE WE sure we are talkng about the port read frequency being only 10hz? I remeber Brian saying that the ports are read at about 2/3 of the kernal frequency.

How else would it be able to read RPM or encoders acurately.

NOW 10hz is the update rate for the VB/macro system and I thought Brains were faster than Macros.
I also remember testing the faster update rates 50hz and up (nice)
.

« Last Edit: May 08, 2010, 03:36:30 PM by BR549 »

Offline Hood

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Re: input read frequency?
« Reply #13 on: May 08, 2010, 04:27:50 PM »
What I understand it to be, things like index for threading, probably Homing etc that are part of the driver are very fast, probably kernel speed,  but other things like normal I/O are at Machs update speed which is 10Hz. Brains themselves are fast but Mach reading of them limits them to 10Hz.
But as said that is just my understanding and as I have never talked about it to Art or Brian so I am just guessing really.
When messing with Rev4 the first thing you notice is the speed of the DROs counting, much quicker and clearer. Kind of like the difference between a set of Mitutoyo digital callipers and cheap Chinese ones, they both end up at the same place but you can actually read the numbers on the Mits as you move it.
Hood

Offline stirling

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Re: input read frequency?
« Reply #14 on: May 09, 2010, 05:53:43 AM »
Hmmmm - I think we're maybe getting there. I'm beginning to suspect that MACH reads it's inputs much faster than 10Hz but that WE via VB or whatever can only access them at 10Hz or about - simply because that is the "activation" frequency of VB. Brains may be faster and perhaps plugins even faster but as I know nothing about either I can't comment. Certainly the index input MUST be read much faster, I suspect it's not alone not least because you can't just read 1 bit of a port - you get 8 bits min whether you make use of them or not. Clearly it makes sense that THC and probe inputs (and probably others) should be as fast as poss. Homing however probably doesn't actually need to be AS fast because it's a two stage process - fast followed by slow. The only crucial read is as it backs off the switch and this as we know is done sloooooowly - giving plenty of time for a read. Also as Hood has previously said I think - it's consistancy/repeatability that matters with home. Home is where home is and as long as it's the same each time - job done. Thanks for your input folks - I'm getting a better understanding now - I think!

Cheers

Ian
Re: input read frequency?
« Reply #15 on: May 09, 2010, 09:09:18 PM »
I'm probably a bit slow and everyone else already knows this but... Re: probing - this must mean that in order to probe at the best resolution your machine is capable of you MUST probe at less than 10 steps per second right?

Ian

Probing is a completely internal operation, and probe input is sampled at kernel speed.  The 10Hz is the macro-pump rate, which has nothing to do with probing.

Regards,
Ray L.
Regards,
Ray L.

Offline stirling

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Re: input read frequency?
« Reply #16 on: May 10, 2010, 04:56:44 AM »
I'm probably a bit slow and everyone else already knows this but... Re: probing - this must mean that in order to probe at the best resolution your machine is capable of you MUST probe at less than 10 steps per second right?

Ian

Probing is a completely internal operation, and probe input is sampled at kernel speed.  The 10Hz is the macro-pump rate, which has nothing to do with probing.

Regards,
Ray L.
At this point in the thread maybe so Ray (see my last post above yours) but at the time I posed the question the thread wisdom was that ALL inputs were read at 10Hz.

That said...
Probing is a completely internal operation
generally yes - but not in a dynamic probing routine and then the 10Hz macro rate really bites you in the ar*e.

Cheers

Ian
« Last Edit: May 10, 2010, 05:34:44 AM by stirling »
Re: input read frequency?
« Reply #17 on: May 10, 2010, 10:07:18 AM »
I'm probably a bit slow and everyone else already knows this but... Re: probing - this must mean that in order to probe at the best resolution your machine is capable of you MUST probe at less than 10 steps per second right?

Ian

Probing is a completely internal operation, and probe input is sampled at kernel speed.  The 10Hz is the macro-pump rate, which has nothing to do with probing.

Regards,
Ray L.
At this point in the thread maybe so Ray (see my last post above yours) but at the time I posed the question the thread wisdom was that ALL inputs were read at 10Hz.

That said...
Probing is a completely internal operation
generally yes - but not in a dynamic probing routine and then the 10Hz macro rate really bites you in the ar*e.

Cheers

Ian

Ian,

I don't know what you mean by "dynamic probing routine", but if you're using G31, it takes a step, then checks the PROBE input.  The 10Hz rate has nothing to do with it.  Were this not true, it would be absolultely impossible to probe at 50IPM, as I routinely do, and get 0.0001" repeatability.  If you're directly monitoring the PROBE input with any kind of macro, then you ARE subject to the 10Hz rate. 

Regards,
Ray L.
Regards,
Ray L.

Offline stirling

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Re: input read frequency?
« Reply #18 on: May 10, 2010, 11:18:50 AM »
Ray

I'm not disputing anything you say. As I've already said, we established this earlier on in the thread. ;)
By dynamic probing routine I mean one that determines at run time what it's next step will be based on previous steps.

But riddle me this. Why doesn't Mach *appear* to work in the same way with regards it's THC UP/DOWN inputs i.e. take a step and then check THC UP/DOWN ?

Cheers

Ian
Re: input read frequency?
« Reply #19 on: May 10, 2010, 11:33:21 PM »
Ray

I'm not disputing anything you say. As I've already said, we established this earlier on in the thread. ;)
By dynamic probing routine I mean one that determines at run time what it's next step will be based on previous steps.

But riddle me this. Why doesn't Mach *appear* to work in the same way with regards it's THC UP/DOWN inputs i.e. take a step and then check THC UP/DOWN ?

Cheers

Ian

Because torch height isn't controlled by G31....  It's a completely different, and less accurate, control loop.  ONLY G31 behaves as I described.

Regards,
Ray L.
Regards,
Ray L.