'tolerance' for STOP logic

[squarewave]

I an working with my Wire EDM installation to fine tune my EdgeFind routine. This involves approaching the part until contact is made, backing off until contact is lost, then reducing the feedrate significantly and approaching the part again until contact is made.

My logic uses POSITION and WAITUNTIL STOP. There is logic in the INPUTIO that issues a STOP when contact is made. During the initial approach at 5 IPM, everything works fine. During the slow approach at .05 IPM, STOP seems to be immediately satisfied, and logic continues past that point - even though the machine is obviously still moving. I have played around with various slow feedrates and have found STOP seems to be anything less than .1 IPM. In other words, my routine works fine if I use a feedrate of .1 or higher, and doesn't work if I use .09 or lower. I thought STOP meant stopped (0 IPM).

I thought that perhaps the machine had not accelerated up to speed before the WAITUNTIL STOP was executed, so I put a SLEEP command before it to make sure. After the SLEEP was finished, the logic just went straight through the WAITUNTIL STOP even though the machine was moving.

Is there a place where I can specify what speed "STOP" is? During burning of thick pieces, these slow feedrates are not uncommon and I can see this being a problem in the future.

Thanks for any thoughts!

[Al_The_Man]

It would'nt be your servo tuning would It? Try the native ST command and see if it stops as this should turn off the servo's, although this a 'decelarated' stop so make sure your decel is as low as possible but at that speed it should be very minimal.
Al.

[squarewave]

Hi Al -

Thanks for the reply. I don't think it is tuning related as I have got them tweaked pretty good.

The Camsoft STOP command works fine - no motion after it is issued. That makes me think the Galil ST will work fine as well.

The problem is with the STOP logical when used in conjunction with a WAITUNTIL. During the slow approach, my INPUTIO file hasn't issued the STOP command (because contact has not been made yet) and the MACRO file just blows on past the WAITUNTIL STOP line.

[Al_The_Man]

It almost sounds like the WAITUNTIL STOP is seeing an 'in positition' band of so many counts. Therefore if the in position band is wide enough the logic will continue. Its been a while since I used Camsoft so I could be wrong.
This is the logic they gave me for the start of a G31 command probe design.
Example for CNC Lite/Plus When using:

(1) a Digital style touch probe of any brand
(2) a G31 Fanuc style skip stop cycle
(3) a Aux digital I/O card for fastest digital signal
(4) it connected to the first aux input #32
(5) a high DECEL value to stop fast
(6) a high feedrate or F word in program
(7) no machine, tool, job or fixture offsets

Call this macro from G31 in the GCODE.FIL file.

[Probe Digital Teach]
!' Example digital style touch probe of any brand
!' G31 Fanuc style skip stop cycle
!' Set high DECEL value to stop fast
!\57=f ' save current feedrate
!MACHGO x;y;z ' 3 axis example
!WAITUNTIL STOP
!IF\31=0THEN EXIT ' Probe not hit
!\31=0
!MACHHOMEZ \55 ' location of Z when probe hit
!MACHGO ;;{\55+.05} ' back away in Z.050
!WAITUNTIL STOP
!FEEDRATE 25 ' set feedrate very slow
!MACHGO ;;{\55-.05} ' come back to touch part again
!WAITUNTIL STOP
!TEACH
!FEEDRATE \57 'reset feedrate back to what it was

Add this line of logic to your INPUTIO.FIL file:

!IF#32=0THENSTOP:\31=1

Al.

[HuFlungDung]

You might also be able to command the Galil card directly within your logic, using the "COMMAND" command, followed by the Galil two letter command.

It is also possible to query the Galil for certain states, and loop your Camsoft logic to wait for the Galil to return the proper value. This is fairly involved to figure out, but the potential is there.

Here is a snippet from a macro I wrote to run a lathe single point threading routine from a stand alone subroutine that resides in Galil memory, but runs via the Camsoft interface. This does not translate directly as the answer to your needs, but just serves as an example for taking control of the Galil without having Windows messing around with the rate of your logic execution:

'Go into hardware threading loop Galilthread.dmc
LABEL1 THREADING DIRECTLY FROM GALIL HARDWARE;11
ACCEL 1;101376 ECEL 1;153600 :RAPIDSPEED 1;\201
ACCEL 2;101376 ECEL 2;153600 :RAPIDSPEED 2;\202
\888=1
SUSPEND INPUTS
BUTTON13 IN;NORMAL I/O SUSPENDED;12
COMMAND XQ#GALIL1,0
SLEEP .25
COMMAND ENABLE=1
:QUERY
COMMAND FPASS=?
RESPONSE \832
\832={INT(\832)}
\835=CLEANUP PASS (NO ADDITIONAL TOOL DEPTH) \832 OF 2
IF\832>0THEN LABEL1 \835;11 :GOTO :G33STATUS
COMMAND REPEATS=?
RESPONSE \833
\833={INT(\833)}
\834=GALIL THREADING SUBPROGRAM ROUGHING PASS \833 OF \156
LABEL1 \834;11
:G33STATUS
COMMAND FLAG=?
RESPONSE \33
IF\33<>1THENGOTO :QUERY
RESUME
BUTTON13 OUT;CHUCK BARRIER;2
\175=0
DISPLAY4 {\273*f}
RAPIDSPEED 1;\201 :RAPIDSPEED 2;\202
LABEL1 THREADING COMPLETED;11
\888=0

[squarewave]

Al -

That routine must be what I started with, because mine looks nearly identical. The only difference is that I use POSITION after I get the current location with MACHHOME and apply a delta. The advantage to POSITION is that I can make the axis (x or y) a variable so I don't have to repeat a lot of code. I also have a direction variable (+ or - direction) since my edgefind has to be able to find an edge in +Y, +X, -Y, -X. Where they slow the feedrate down to 25 is where I am slowing it down to .1 or less.

That "position band" is what I am hoping to find, except more like a "velocity band". I feel like the STOP logical is being satisfied if the current motion is below some small value - in my case it seems to be around .1 IPM. If I have access to that value (like the TOLERANCE value in the CNC setup), I'd set it at .001 or so.

Hu -

Thanks for the example. I'll have to dig out the Galil command reference and see if there is something I can query for a zero velocity or if a STOP has been issued. If so, I can just make a tight loop after the POSITION command to keep querying until motion is stopped. That would be a direct replacement for the WAITUNTIL STOP Camsoft command.

Thanks for the insight guys!

[Carlo Rechi]

I have solution.

try to put 2 WAITUNTIL STOP in a row like this

WAITUNTIL STOP:WAITUNTIL STOP

This will make sure it is stopped

Carlo