RSLogix/Kinetix Homing and Limit Switches

OOPer · Jul 20, 2011

I am new to these Kinetix (6500) modules, and I am trying to figure out a couple of things

1. How to home the motor (with absolute encoders) to a limit switch. We have 2 overtravel limit sensors attached. I am trying to home to one of them. So, I jumped one of the sensors into DI for the module and set that to Home in module config, but issuing the home command does nothing. I tried the hook-up test to find the marker, but it false-finds it almost instantly after I start moving the motor. What am I missing?

2. The overtravel sensors work great, as in the module faults out as soon as I hit the sensor. But, how do I recover from this with out manually having to push the motor/load away from the sensor? Shouldn't I be able to servo the other direction from the limit?

thanks

iant · Jul 21, 2011

I don't know the system but with an absolute encoder you amy need to home it first.
disconnect the drive belt or coupling and return the motor to it's 'Zero' position. this might be the cause

bernie_carlton · Jul 21, 2011

When I last used Kinetix the limits action was still messed up. If you hit a limit your code must clear the fault, disable ALL limits, drive in the opposite direction until off the limit, stop then re-enable the limits.

Even after much asking they had not implemented, even as one of many choices, the obvious mode of allowing movement in the opposite direction without having to go through all that.

Hopefully it has changed and that option has been added but I'm not holding my breath.

steveb1475 · Jul 21, 2011

What are your settings on the homing tab? Most likely your mode is absolute. Your only sequence selection with absolute is immediate. You will need to write a sequence to execute a MSF (turn off the drive) -> MAH (home the drive in absolute mode) -> MSO (turn the drive back on) -> SSV to change the homing mode to active -> SSV to change the home sequence to switch homing -> MAH to home the axis to your switch. Use the status bits (.dn .pc etc) from your motion control tags and the .ConfigUpdateInProgress (for the SSV commands) from your axis tag to make sure one command finishes before executing the next. Hope this makes sense.

Edit:
I think I got it backwards, the first homing will be in Active mode Switch sequence. The second should be absolute or you won't get the .AbsoluteReferenceStatus bit in your axis tag. Watch the .DriveEnableStatus tag to make sure your drive is off when you do the MSF and to make sure it is back on after the MSO.

OOPer · Jul 21, 2011

bernie_carlton said:
When I last used Kinetix the limits action was still messed up. If you hit a limit your code must clear the fault, disable ALL limits, drive in the opposite direction until off the limit, stop then re-enable the limits.

Even after much asking they had not implemented, even as one of many choices, the obvious mode of allowing movement in the opposite direction without having to go through all that.

Hopefully it has changed and that option has been added but I'm not holding my breath.

That sounds like a messy approach. How would one disable the limits in the code?

steveb1475 said:
What are your settings on the homing tab? Most likely your mode is absolute. Your only sequence selection with absolute is immediate. You will need to write a sequence to execute a MSF (turn off the drive) -> MAH (home the drive in absolute mode) -> MSO (turn the drive back on) -> SSV to change the homing mode to active -> SSV to change the home sequence to switch homing -> MAH to home the axis to your switch. Use the status bits (.dn .pc etc) from your motion control tags and the .ConfigUpdateInProgress (for the SSV commands) from your axis tag to make sure one command finishes before executing the next. Hope this makes sense.

Edit:
I think I got it backwards, the first homing will be in Active mode Switch sequence. The second should be absolute or you won't get the .AbsoluteReferenceStatus bit in your axis tag. Watch the .DriveEnableStatus tag to make sure your drive is off when you do the MSF and to make sure it is back on after the MSO.

Homing is set to Active with Switch as Sequence. I don't know what position and offset values in there mean, so I just used 2mm for position and 1mm for offset , and also set the Direction to Forward-BiDirectional

I tried homing using the MAH command from Motion Direct Commands wizard, it returns success instantly as if it found the switch right away.

Also, what is a Registration and how is it different from Limit swtich?

bernie_carlton · Jul 21, 2011

Check Knowledgebase 21499

weolson71 · May 19, 2014

OOPer said:
That sounds like a messy approach. How would one disable the limits in the code?

Homing is set to Active with Switch as Sequence. I don't know what position and offset values in there mean, so I just used 2mm for position and 1mm for offset , and also set the Direction to Forward-BiDirectional

I tried homing using the MAH command from Motion Direct Commands wizard, it returns success instantly as if it found the switch right away.

Also, what is a Registration and how is it different from Limit swtich?

I am having the issues, I have a Kinetix 6500, that was pushed on us by a supplier, its rather simple application, just driving a screw to a point holding for a moment and comming back, to a home position, but i hit a limit every so often and cannot figure out how to hit a home button and drive the servo back to its home position?? This is frustrating

RSLogix/Kinetix Homing and Limit Switches

OOPer

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iant

Lifetime Supporting Member + Moderator

bernie_carlton

Lifetime Supporting Member + Moderator

steveb1475

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OOPer

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bernie_carlton

Lifetime Supporting Member + Moderator

weolson71

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