limit switch error fool-around

i'm running emc with a gecko540 and i'm only just ready to start
but for my lack of information.

the latency was my first prob but i soon fixed that.
i then ready the entire HAL instructions because i couldn't find the on button

anyway the problem i have now is my limit switches they seem to require a different setting each time i turn them on. one day x inversed, y z normal
the next all inversed. i keep bouncing between emc and the configuration panel and then when i jog it hits the switch and repeats the limit switch error.

one theory i have is that my config is set for two open switches in parallel and the gecko takes two closed switches in series. i don't know. but it is very erratic .

The general rule is that you don't want your limit switches wired NO (normally open) and parallel. The rational is that if a wire broke, you wouldn't notice until you ran into a limit switch and it didn't work. One can also come up with a scenario where a circuit with NC switches wired in series could also fail in an unnoticeable manner, but there are fewer points where the circuit could fail in an undetectable manner.

Alan

why would a limit switch trigger an error at all.

Quote:

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Originally Posted by draughted

why would a limit switch trigger an error at all.

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Because you are not supposed to hit the limit switches. If you hit a limit switch, you have created an error.

That is why you have to tell emc2 if you are using limit switches as home switches as well. So that it can ignore the limit switch error and treat it as the home switch during a homing operation.

Alan

ok thanks, however it seems in my ini file that it is all ready set to ignore-limit-switch
and homing becomes a problem.

it always sees the first home as an error

Quote:

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Originally Posted by draughted

ok thanks, however it seems in my ini file that it is all ready set to ignore-limit-switch
and homing becomes a problem.

it always sees the first home as an error

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Here is some of the info from my .ini and .hal files.

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From my .ini file
#+ First axis
[AXIS_0]

HOME_OFFSET = -0.1
HOME_SEARCH_VEL = -1.500
HOME_LATCH_VEL = 0.250
HOME_USE_INDEX = NO
HOME_IGNORE_LIMITS = YES
HOME_SEQUENCE = 1

# the same basic info is included in each axis

### From my .hal file the pin and signal setup for estop and limits

# create a signal for the estop loopback
net estop-ext <= parport.0.pin-10-in-not
net estop-out <= iocontrol.0.user-enable-out
net estop-ext => iocontrol.0.emc-enable-in

# create a signal for the limit switches
net both-home-x <= parport.0.pin-11-in
net both-home-y <= parport.0.pin-12-in
net both-home-z <= parport.0.pin-13-in

# create a signal for the x home and x limit switches combined
net both-home-x => axis.0.neg-lim-sw-in axis.0.pos-lim-sw-in axis.0.home-sw-in

# create a signal for the y home and y limit switches combined
net both-home-y => axis.1.neg-lim-sw-in axis.1.pos-lim-sw-in axis.1.home-sw-in

# create a signal for the z home and z limit switches combined
net both-home-z => axis.2.neg-lim-sw-in axis.2.pos-lim-sw-in axis.2.home-sw-in

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Alan

it is almost too embarising but it seem that i mistakenly labeled the limitswitch terminals in the opposite order to their being wired.
making the home sequence a shambles when the wrong limit activates.

Well, at least you discovered what was causing the problem.

Alan

Don't feel like the Lone Ranger I had cross up the encoders on Y and Z . Just could not figure out why I could change the direction of Y :-)

Quote:

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Originally Posted by draughted

ok thanks, however it seems in my ini file that it is all ready set to ignore-limit-switch
and homing becomes a problem.

it always sees the first home as an error

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Hi,
This is also the case with one of my axes. Always error on the forst Homing after power on. After the first one everything seems to be working as expected.
Have you goeetn this issue solved?

regards Chris