Rapid over ride percentages

Im having a hard time wrapping my head around the maximum velocity concept of halui. My goal is to use a BCD rotary selector to select 10,25,50,75 and 100% rates of rapid travel. I would like to direct set them similar to this

if(((modesel_pos)==1||(modesel_pos)==2)&&(rapid_or_pos)=1)
{
rapid_or_en=1;
rapid_or_dir=1;
rapid_or_per=.1
}


with the following hal connections
pin in s32 rapid_or_pos; // connected to wsum.0.sum = controlpanel.0.rapid-or=pos
pin out bit rapid_or_en ; //halui.max-velocity.count-enable = controlpanel.0.rapid-or-en
pin out bit rapid_or_dir; // halui.max-velocity.direct-value = controlpanel.0.rapid-or-dir
pin out s32 rapid_or_per; // halui.max-velocity.counts = controlpanel.0.rapid-or-per //percentage of maximum rapid

the modeselect and rapid or pos are connections to actual bcd selectors that are w summed , and used for setting conditions.

Is there a way to simply direct set the max value of rapid travel with out using the increase decrease pins? The manual and man pages are short on info. Would I be better off using halui.max-velocity.counts or halui.max-velocity.scale. It seems as this is set up more for a rotary encoder. All and any help is always appreciated.

Thank you bunches. Im pretty sure what I have is gonna work. Who I send a suggestion to for some minor modifications to the documentation? I have a small log of things that might be helpful to other folks. Thanks again.

One little detail about this suggestion is that Max-velocity is not in percent.
it is 0 to MAX_VELOCITY in the INI file.

if you choose the values in the mux correctly you can get percentage divisions,
but if you change the max velocity in the INI file you will need to adjust the mux values.

Chris M

Chris ,

Id like to bug you some about this. In johns example he is assigning what appear to be percentages to halui.feed-override.counts. That being the case, it would stand to reason that 10 would produce 10% of rapid travel, or a rate of 40ipm on a 400 ipm rate. Is this correct?

I approached this differently, I simply am looking for 5 rates of rapid travel which are assigned by a bcd selector. My stuff is written a component, for my whole operator panel. It has a section for the rapid over ride. Using Johns feed over ride example, if I assign a value of 10 to halui.max-velocity.counts with a scale of .01 assigned to halui.max-velocity.scale, on a 400 ipm max rapid, I should get 40 ipm? If not what about this am I missing?


I was planning on using analog pots for feed and spindle override, and was curious how to go about getting this to work. Thanks...

yes feed override and spindle override are in percentage
..well actually 1 is full speed (notice that John scaled feed override by .01 to account for that.

Max velocity is not done that way - I don't know why it was chosen to be like that. it is in user units per second as an absolute value

setting counts 10 with .01 scale = 0.1 unit per second or 6 units per minute

So to get counts to be percent:

divide max velocity in units per second by 100
400 / 60 = 6.6667
6.6667 / 100 = .066667

Then counts will be in percent.
If you change the INI file max velocity then you must recalculate this.

HALUI looks for MAX_VELOCITY= under [TRAJ], if it can't find it there it looks under [AXIS_0]
any other max velocity settings in the INI are either wrong and ignored or used for the GUI.

By the way Max velocity is NOT rapid override.
If you turn max velocity down enough it affects feed rate also.

Chris M

Thanks for clearing that up, which brings a new question, what is available for backing down rapid travel and at what percent of max velocity does adjusting the max velocity affect feed rates? I wouldnt ask if I didnt have to....and thanks

JR

There is a reason they named it max_velocity_override instead of rapid_override.

It sets the absolute max velocity linuxcnc will allow, in any mode but homing.

So if you set max_velocity_override lower then your current feed rate it will limit that feed rate.

Note that setting feed_override affects rapids also - annoying.

in linuxcnc 2.5.x that is how it is.
in 2.6 feed override will not affect rapids but max_velocity_override will still limit feed rate (not quite so annoying)

How were you going to get the analog signal into linuxcnc for your feed and spindle override?

Chris M