On 10/28/2019 12:07 PM, John Dammeyer wrote:
How is the ESTOP chain enabled again on your machine? I would imagine you have
a relay in series with the ESTOP button NC circuit? So if clicking the red
estop icon button on LinuxCNC you'd break the ESTOP chain just like a servo
fault? How do you close that relay again?
Each servo amp has a relay that opens when the amp goes to
fault status. There is also a fault relay in the spindle VFD,
and a red manual button.
Or does the FAULT from the servo go away on removal of power which then closes
the ESTOP chain again?
The servo amps have a fault reset button on them that has to
be pressed to clear it. There are red LEDs on the amp, so I
can see which one faulted.
Does a limit switch also act as an ESTOP and shut off motor power or just the
Machine ENABLE?
I do not have limit switches on my machine. Only home
switches and the soft limits on LinuxCNC.
In the case of a DC servo, say a driver transistor fails on and the motor heads
at full speed into the limit switch. Theoretically the following error should
happen first so the system sees the fault. But if it doesn't remove the HV
then the motor continues possibly damaging something or someone.
Yes, that is a potential problem. Of course, it actually
requires TWO transistors to fail to connect the motor to the
DC supply.
I have never had this happen, but it is a concern.
Jon
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