Master and Slave axes in EMC2+Montec
08 Nov 2010 16:25 #5164
by Schnitti
Replied by Schnitti on topic Re:Master and Slave axes in EMC2+Montec
Hi John,
this is a real picture from build up my machine. It is a DIY router.
this is a real picture from build up my machine. It is a DIY router.
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10 Nov 2010 17:01 #5201
by andypugh
Replied by andypugh on topic Re:Master and Slave axes in EMC2+
You have an interesting hybrid hal file there 
Are you wanting to use gantrykins or trivkins?
As a first experiment, change gantrykins to trivkins in the hal file, then change this section:
To:
That will (well, should) give you three axes linked to 4 stepgens, but with no way to operate the two X motors independently.
What is happening is that the modified code uses the already defined xpos-cmd signal from the master X axis as the input to the extra stepgen.
There is no indpendent feedback from that stegen, but as they are identical that won't matter (it almost never matters anyway, stepgen feedback only ever detects a stopped stepgen thread or a thread frequency that is too slow for the commanded speed, and generally you hit mechanical limits first).
Alternatively, to use Gantrykins you should make these changes:
Add this code immediately after loadrt gantrykins
Then edit the axis3 stuff to this:
(The only difference is to make all the signal names unique)
The Gantrykins version will start up in joint mode, and won't let you switch to XYZ mode until the axes are all homed. It is well worth making sure you have a working homing sequence as jogging two axes to home at the same time is impossible.
Are you wanting to use gantrykins or trivkins?
As a first experiment, change gantrykins to trivkins in the hal file, then change this section:
setp stepgen.3.position-scale [AXIS_3]SCALE
setp stepgen.3.steplen 1
setp stepgen.3.stepspace 1
setp stepgen.3.dirhold 230700
setp stepgen.3.dirsetup 230700
setp stepgen.3.maxaccel [AXIS_3]STEPGEN_MAXACCEL
net xpos-cmd axis.3.motor-pos-cmd => stepgen.3.position-cmd
net xpos-fb stepgen.3.position-fb => axis.3.motor-pos-fb
net x1step <= stepgen.3.step
net x1dir <= stepgen.3.dir
net xenable axis.3.amp-enable-out => stepgen.3.enableTo:
setp stepgen.3.position-scale [AXIS_3]SCALE
setp stepgen.3.steplen 1
setp stepgen.3.stepspace 1
setp stepgen.3.dirhold 230700
setp stepgen.3.dirsetup 230700
setp stepgen.3.maxaccel [AXIS_3]STEPGEN_MAXACCEL
net xpos-cmd => stepgen.3.position-cmd
net x1step <= stepgen.3.step
net x1dir <= stepgen.3.dir
net xenable stepgen.3.enableThat will (well, should) give you three axes linked to 4 stepgens, but with no way to operate the two X motors independently.
What is happening is that the modified code uses the already defined xpos-cmd signal from the master X axis as the input to the extra stepgen.
There is no indpendent feedback from that stegen, but as they are identical that won't matter (it almost never matters anyway, stepgen feedback only ever detects a stopped stepgen thread or a thread frequency that is too slow for the commanded speed, and generally you hit mechanical limits first).
Alternatively, to use Gantrykins you should make these changes:
Add this code immediately after loadrt gantrykins
setp gantrykins.joint-0 0
setp gantrykins.joint-1 1
setp gantrykins.joint-2 2
setp gantrykins.joint-3 0Then edit the axis3 stuff to this:
setp stepgen.3.position-scale [AXIS_3]SCALE
setp stepgen.3.steplen 1
setp stepgen.3.stepspace 1
setp stepgen.3.dirhold 230700
setp stepgen.3.dirsetup 230700
setp stepgen.3.maxaccel [AXIS_3]STEPGEN_MAXACCEL
net x1pos-cmd axis.3.motor-pos-cmd => stepgen.3.position-cmd
net x1pos-fb stepgen.3.position-fb => axis.3.motor-pos-fb
net x1step <= stepgen.3.step
net x1dir <= stepgen.3.dir
net x1enable axis.3.amp-enable-out => stepgen.3.enable(The only difference is to make all the signal names unique)
The Gantrykins version will start up in joint mode, and won't let you switch to XYZ mode until the axes are all homed. It is well worth making sure you have a working homing sequence as jogging two axes to home at the same time is impossible.
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