6TB IS IT OK TO CHANGE PARAMETERS?

[metalart]

HAVE A CHNC LATHE, BEEN TRYING TO FIQURE OUT A "420 Z AXIS" ALARM AT START UP, NO AXIS MOTION, ALARM POPS UP RIGHT AWAY. CHECKED TO MANY THINGS AND NOT THE RIGHT ONE. SEEN A POST ON THIS SIGHT ABOUT CHANGING PARAMETERS TIED TO AXIS. I COULD SEE THRU MY DGNOS SCREEN PARA 801 AT 70-80, SO CHANGED PARA 75 FROM 40 TO 100, AND ALARM IS GONE. WHAT DID I JUST DO? IS IT OK TO RUN?

THIS SIGHT IS GREAT, JUST FOUND IT TODAY!!!

[da21]

my book relates alarm 410 & 420 to parameter 74 & 75 as quote :

74 = x-axis
75 = z-axis

Limitation value of position deviation amount at stoppage .
(STPEX for X Axis and STPEZ for Z axis )
Standard setting 500

or put another way
the position deviation excess alarm has over shot ( or under shot ) it's target
through it's limit range setting , so for instance u asked it to move 1000 counts and with limit set at 10 , gives you a max movement allowed of 990 to 1010 on the resolver given the velocity etc ,but you have over shot or under shot this range , i.e it's moved 1050 counts , hence giving you the error

could just be a one off problem . as you noticed the the value was lower than the default setting , or previous programming error , or could be a sign of ballscrew wear , or just running too fast etc .


Dave

[metalart]

Thanks Dave, Do you have any more info on the parmeters for this machine. As you can see I posted a year ago, and you are the first that has had the know as to what these parameters are.

[da21]

yes i have most of the information lurking around , and a few maintence manuals

pm me if you wish etc


Dave

[Dan Fritz]

Have a look at diagnostic 801 again. It should read about zero when the machine is not moving. This is the "following error" of the Z axis servo. To adjust it to zero, take a small screwdriver and look for a potentiometer labeled "RV2" on the Z axis servo board and turn it a wee bit until that diagnostic is oscillating around "0". This is a "drift" adjustment on the servo. You can do the same thing for the X axis by tweaking RV2 on the X servo board and watching diagnostic 800.

If the "drift" of the Z servo (following error when the servo is stopped) is greater than parameter 75, you will get an alarm and the servo will shut down. Making the parameter bigger just permits a larger error and does not really correct the problem.

The system 6 also has a feature called "automatic drift compensation" which automatically makes the same servo adjustment internally. To use it, set parameter 006 bit #7 (the bit on the far left) to a "1", then turn the control off and back on again. The parameter will go back to "0" automatically, but the drift should be zeroed out for you. The RV2 pots on the servo boards also adjust drift, but that's the manual way of doing it.