Messages

41

General Mach Discussion / Re: Error Trapping in Button Script

« on: July 24, 2009, 05:34:31 PM »

Here's what is in the Mach Manual:

"In response to this command, the machine moves the controlled point (which should be at
the end of the probe tip) in a straight line at the current feed rate toward the programmed
point. If the probe trips, the probe is retracted slightly from the trip point at the end of
command execution. If the probe does not trip even after overshooting the programmed
point slightly, an error is signalled."

However, I believe what you are saying is correct, because I have not seen it move due to G31 after the probe touches. But again, I was simulating the probe by touching two wires together so I thought perhaps it was moving ever so slightly and when it did not see the probe break contact it raised an error. Assuming you are correct, I am guess I will have the same wierd probel with the moves after G31 when I truly do use a touch plate. I suspect this may be a SmoothStpper issue, but will investigate more to see if I can better characterize exactly what is happening.

42

General Mach Discussion / Re: Error Trapping in Button Script

« on: July 24, 2009, 05:04:21 PM »

Here's a more detailed description. I have a zero touch plate routine that many have been using. This code should never drive the bit into the workpiece. I am also using a SmoothStepper (SS) which may actually be the problem. However, I am aslo doing something that I am suspecting may be casuing an error and cofusing Mach or the SS. Rather than use a touchplate, I have simply shorted two wires togther to simulate the plate being touched while testing this feature. I have read that the G31 code will actualy retract the bit a very short distance after the probe fires. My hand shorting of two wires wouldn't simyulate the probel breaking contact at just the irght time for this small retraction so today I started wondering if I was causing a problem with my test method and then wondered if I could error trap. I am not at the machine today, so I can't simply try a real touchplate, although that scrares me a bit since this sometimes drives toward the table when the button routine performs the final retract. Another person also sent me a message that they were using the same routine I am using and it normally works OK. However, one time they had the touch plate so far away that the bit failed to contact the plate by the end of the G31 move. They hit zero again and after the bit hit the plate, the machine then drove the bit very hard into the touchplate/workpiece. They are not using a SS, so I thought that perhaps he too had an error condition that our button routine needs to trap.

Sorry for the lengthy explanation. Just thought it better to give the full picture.

43

General Mach Discussion / Re: Error Trapping in Button Script

« on: July 24, 2009, 03:48:52 PM »

I have had a problem where the probe actually drives the bit toward the workpiece when retracting after the probe touches. The retract code uses G0 to re-position. I have seen the it uses the appropriate z coordinate for the G0 comand, yet it travels the wrong direction. I was wondering if an error occurred and if I could truly trap that error then I could abort the retract portio of the code. I am new to button scripting so I was wondering if there is an onerror type capability in the button scipting.

44

General Mach Discussion / Error Trapping in Button Script

« on: July 24, 2009, 03:31:44 PM »

The G31 code (linear probe) refers to errors that may occur if the program point is less than .01" from the start point. Is there a way to add error checking in the VBscript button code to trap errors?

45

SmoothStepper USB / Re: Slaved axis homing with the SS

« on: July 21, 2009, 02:26:11 PM »

I am using a SS with a gantry that has the A axis slaved to Y. If I ref all home, everything normally work fine. However, every now and then the A-axis will keep running while it is backing away fromthe A-limit switch. I have to hit e-stop. I finally figured out that this happens if the ganrty is racked such tha the A-limit is hit before the Y-limit.

46

Brains Development / Re: Wirting Message to Status Area via Brain

« on: July 18, 2009, 01:15:16 AM »

Thank you for the reply.

I read your user guide for Brains which was very helpful.
 
I have another question. I'd like to update a local brain variable with an encoder DRO value only when  another condition exists. The other condition is the status of an ouput signal. Basically I am trying to do an IF statement. If the output is high, then update the brain variable with the encoder DRO vlaue; otherwise leave the variable at the same value it was before. I don't really see how to logically combine two rows and have the output of that combination some value other than the logical combination of the two inputs. I think I am trying to do more than what a brain is designed to do.

Thanks,
Kent

47

General Mach Discussion / Re: Brain Refresh Rate

« on: July 17, 2009, 10:41:11 AM »

I posted the following question to the Brains forum, but it seems that not many monitor that thread. So I'll ask it here.

"What is the OEM code to write text to the "Status" area located at the bottom of Mach's Program-Run screen?"

I'd like to write a status message when the "Racking Control" brain issues an e-stop so that I know why the system was stopped.

48

General Mach Discussion / Re: Brain Refresh Rate

« on: July 17, 2009, 09:23:17 AM »

Thank you guys for the answers. Thanks Hood for confirming the answer. I will just look forward to version 4. Any idea of when it will be released?

49

General Mach Discussion / Re: Brain Refresh Rate

« on: July 17, 2009, 01:41:36 AM »

Is there a way to confirm the 10 Hz rate? Second question would be is there any way to change the refresh rate, which I am guessing there is not. I wrote a brain to detect a count difference on two encoders to detect racking of a gantry and then e-stop if the difference is greater than a given amount. Works great except that the gantry may be travelling at 10 inches per second. If the brain refresh rate is 10 Hz, that means the gantry will rack by an inch before the brain issues the e-stop.

50

General Mach Discussion / Brain Refresh Rate

« on: July 16, 2009, 11:46:52 PM »

What is the refresh rate of a brain? Brains are said to run fast, but how often do they run?