can i make an axis move?

[matttargett4]

hi all,

ive been looking at the list of options for lobe termination to try to find an option that will move an axis and i cant find it, it may be obvious so i thought i would ask the people who know, if it cant be done could i do it with a macro pump or vb script, forgive me im not too familiar with them since ihave concentrated on brains up to now.

Thanks in advance

matt

[Overloaded]

HI Matt,
 You can terminate a Brain with a Button Press that can move an axis...like "Homing" an axis or "Go to Safe Z".
I know little about it but you might need to give more specific information about what you are wanting to do.

Regards,
RC

[matttargett4]

ok so a few more details,

i was looking to make an axis move with a proportional response to an input, ideally id like to implement a pid loop with adjustable gain through dros, that part is no trouble since i can read oem dros into a lobe and write the pid loop into the function box which gives me an output value but i cant work out how to make the axis move in response to this value, i would be a start if it were just one way for posative and the other for negative rather than a proportional response.
not sure if you have any ideas?

thanks
matt

[Overloaded]

I'm certain the additional details will help but I'm afraid its a bit over my head.
There are others here that can help I'm sure.
PoppaBear is great with this stuff. Did you see his Brains tutorial in the Members Docs. section ?
Wish you good luck,
RC

[poppabear]

The question in my mind would be this: Would you be be pulling in the Current Axis DRO position then using that as a base input value, run it through the equation of your PID, then add that value as a positive of negative value and have the axis move to that adjusted position??

scott

[matttargett4]

yes thats what im looking to do or a variation on it!

[poppabear]

you will need to post up here your PID equation, plus your dead band if you have one, also the scaling factor that your PID is controlling over.
How your PID value is coming in? i.e. on Analog input over the modbus?

is this something like a Plazma machine in where you are constantly changing the Z ht., depending on the Arc Current as the machine tavels?
Need some operational details to see if you want can be done this way or not.

scott

[matttargett4]

yes this is for a plasma z axis

the anaologue input is coming in from a pokeys device on modbus address 125

not bothered to work out the exact scaling factors yet, i was messing about to see if it could be done, i simlply have a pot connected at the mo to try to make a simple program that will make the axis respond to the pot position forgetting the pid loop for a minute

i have been trying bits and pieces it currently does this relyably

reads the value (Mod 125)

divides by 5

writes it to userdro 1001

Compares user dro1001 to user dro1002 (user entered value in the mach screen)

Here is where i stumble

I have tried writing this value to the z position dro but it wont seem to let me, any user dro is ok but not z position

ive also tried setting a crude threshold value and jogging the axis one way or the other depending on the value relative to the threshold, this works ok until a program is running then the g code seems to over rule it

ive also tried feeding this back into the thc up and down inputs, i can make the led slight but again has no affect on the axis, maybe there is some other criteria i must satisfy for these inputs to work, conicedently what do i do if i want to trigger an input from a brain, i guess i must enable it in the ports/pin window, is that it or do i have to specify a port or pin?

im in the process of trying to get the brain to write g code to move the axis through a macro - simple if the value is above the threshold then write one code and another if it is below the threshold but need to brush up on my scripting etc first.

Id be interested to see how you could do it, clearly reading the forum you are very capable with brains so i thank you for your help

matt

[poppabear]

Matt,

    if your are running G Code you cannot Jog Mach3......  and that is that..............
BUT!!!
You DO have another option, you can have a standard Analog Motor drive your Tourch offset ht. (you can still have an overall Z axis move the entire head up and down, but have a DC motor move the tourch it self up and down by a screw or somthing. You can then have your PID loop control the up/down of the tourch by your current sensor, Purhaps putting a "Slider Resistor" on the tourch so that you can have a resistance to reference for  start ht. then have the pid adjust off of that or something according to the current amount.

NOTE: The Update Loop of Mach is 1/10th of a second, you would probably have better luck having something with a faster scan time adjust your PID like a PLC.

scott

[vmax549]

HIYA SCOTT, I thought mach could adjust z on the fly as a plasma mode?

Just a thought, (;-) TP