Shankar Rao


3 posts in this topic

Dear Experts


We have got End of Line testing machine  to check diameter of brake assembly. This is not in use since last couple of years & unable to contact OEM


Pl refer to attachments ,  there are linear & rotary motors on left and right side .


Linear motors move 3 sets of LVDT probes on either sides towards and away from liner of brake assembly & rotary motors to move LVDTs to three different angular positions of brake assembly along one big gear (to get mean of all three positions as diameter of Brake assembly)


We are able to move and even home all 4 motors (through Initialize Machine option of SCADA) but get error LH Motor negative over travel and hence LH drive gets disabled


Applied emergency and manually moved  LVDT slide to  different positions & tried to Initialize but to no avail

Request to go thro details and suggest remedial on how to overcome LH motor overtravel

Thanks & Regards


This machine has absolute encoder, it appears that reference needs to be reset for LHS as RHS is absolutely fine


Request to go through and share with your technical team for further discussions




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I can't open your software with where I am presently but have you determined if what the HMI calls an Overtravel is a Soft or Hard Overtravel of the Motor in the PLC.

If it's a Hard OT then you're looking at moving the physical limit switch.  Maybe some one bumped it in the idle years.

If it's a Soft OT you're looking to see if your zero is off or if you can change the soft OT in coding.

WHile you're at it make sure someone didn't move the home limits.

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Further to BobLfoot's comment about the physical limit sure also that it hasn't been disconnected/removed. They're usually normally-closed devices so if it's disconnected the drive will think it's at the limit.

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