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Rj3 srvo-231 Chain 2 (0v) abnormal failure

  • Hi All

    I am having issues with chain 2 0v failure. So far I have replaced:

    Teach pendant

    TP cable

    PCB panel board


    I was thinking of replacing the redundant unit next. Any other possible solutions please?

    Thanks :)

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  • yes i did. I swapped the estop unit with from another machine. the robot turned on once but doesnt want to turn on again. there is no green light on the power supply unit. what could be wrong?

  • Chain fault is caused when the safety circuit is not getting both signals at the same time, or missing one. Each safety function has a pair of signals for redundancy. On the Estop board the are EAS (fence circuit, 4 wires), EES (external estop, 4 wires).


    I would start there.

    Also could be wiring from the robots Estop buttons, or deadman switches.

  • oh ok. Am getting error when pressing e-stop on both TP and OP also when changing the mode from Auto to T1 or T2. could it be a broken wire somewhere on the 0v. Also all the externals are jumpered at the moment. For dead man I have replaced the teach pandant and tried, still same

  • Make sure the external safety connections are properly jumped.

    The front panel Mode Keyswitch and the door switch (if you have an A-Style controller) are also part of the enabling for the SVONA (24V) & SVONB (0V) signals.

    If I remember correctly, the system inputs that monitor both run-chains are actually on the amplifier top board.

  • In these cases, I always attempt to isolate Controller from the Field from a 'safety chain' perspective.

    By this I mean disconnection of the external field wiring to the Emergency Stop Board and insertion of either a 'jumper set' or a 'switch box'.

    (You should have access to this schematic in the Controllers Maintenance Manual).


    This way the Controller is isolated from the field.

    If the fault is still showing, then it is localized within the Controller, Teach Pendant and Manipulator.

    If the fault is cleared, then the problem points towards field side wiring and/or peripherals.


    Agreed, this is not always the case, but I recommend this type of method, before going in 'gung ho' and swapping everything in site as sometimes you could introduce further problems by the 'act' of swapping components.


    As HawkME has suggested, safety chains utilize 2 lines of redundancy.

    Usually a 24V and a 0V circuit which must be complete circuits at the same time.

    Any one of these circuits that isn't complete will result in a fail safe state, either because of supply failure, break in the circuit due to resistive/short contacts on switches or wires displaced/shorted.

  • Hi Guys

    Thanks for the support. at this stage none of the external safety components are hooked up. its all local. this is a type A cabinet. Noticed on the panel pcb board that the SVONA (24V) led green light goes off when e-stop is pressed but the SVONB (0V) signals led green light stays on. does this mean that the 0v circuit is not breaking? also the KA1-KA3 relays on the redundant unit does not change state when estop is pressed and goes on chain 2 0v failure. there is a door switch on the amplifier cabinet, the latch is unscrewed from the door and hooked on the switch permanently.

  • Have a look at TBOP14 on the Emergency Stop Board make sure this connection is firm and also check the jumpers (if you are using the internal 24V).

    Also check the Emergency Stop condition outputs:

    ESPB1 and ESPB11

    ESPB2 and ESPB21


    These are the Emergency Stop Condition Outputs relative to the TP and Operator Panel E/Stops which are series linked.

    Both contacts (potential free) should show the same condition:

    - S/C between ESPB1 and ESPB11 when both TP and Operator E/Stops are returning 24V.

    - S/C between ESPB2 and ESPB21 when both TP and Operator E/Stops are returning 0V.

    - O/C between ESPB1 and ESPB11 when either TP and Operator E/Stops have broke 24V.

    - O/C between ESPB2 and ESPB21 when both TP and Operator E/Stops have broke 0V.


    If these are different, then the internal relays may not working, or possibly wiring/fault E/Stops.

    • Helpful

    Hello everyone

    Found the problem. It was the CRM42 cable which was faulty. Ran 2 independent cables from CRM42 and the problem went away. Now need to run some proper cable. thanks for all your support.


    cheers :):)

  • True this is very rare as there is like 3 different sets of cable coming out from one big cable. luckily only the estop cable got damaged (dont know how tho, but the robot has been shifted few times). The SVONA and SVONB led lights were really helpful while diagnosing the issue.


    cheers..

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