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Thread: Question for limit switches and shield in driver cables.

  1. #1
    Join Date
    Sep 2020

    Default Question for limit switches and shield in driver cables.

    Hi all i am new member in this forum.
    Some time ago i bought a totally dismantled prsalpha 96 X48, with all cables cut aparently for a quicker dismantle off the machine, and a bucket with bolts and nuts in it. But that made it easier to transport it.
    Slowly it's starting to look and work again as a CNC machine.
    From what i can find out it's a 2007 model with upgrade to USB controlling the controller card.

    VEXTA ASD 16 A-C drivers, VEXTA ASM98AC - 17.2 motors.
    PRS - A 081 208 00 / 595 controller card version P/N 001003 V 0,8

    From the cut cables i could only use 1 cable for motors - and the original cable for the spindle, so finally i got the 3 remaining cables for motors to work.
    Here comes my questions - seems like the shield off all cables to motors are connected to the output off the corresponding driver for the motor - and from what i can measure seems like the shields are getting 50V AC - is this correct ?
    This 50V AC remain the same when i start the VLD and spindle ( chinese 2,2 Kw spindle and VLD) - but aparently either the 50V AC in the motor cables or the holding torque to motors - generate 24V ac in the shield for the spindle - wooouw trying to ground the shield for the spindle with the 24V AC totally trips controls - gantry motor starts to make strange noises and moves and laptop totally looses connection to the software, and needs a totally reboot.
    Keeping both ends off the shield for spindle cable isolated no probs - spindle can start and stop and axes can be moved - is there a easy fix to ground the shield ?
    I am also concidering to alter the limit switches ( reason the original Bauer limit switches only 1 was still mounted when i bought it so missing 1) from what i can measure the original switch gets 24V DC and when swithed it gives +5V dc out to signal wire. If thats correct isn't it better to mount 2 relays 24 V DC in control box triggered from normally limit switches and let these relays run +5V dc taken from input on controller card to input 2 and 3 in controller card ?

  2. #2
    Join Date
    Sep 2020


    Ooops aparently i made a mistake measuring on limit switches - using +5V don't trigger anything - but ground on controller card trigger input 2 and 3.

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