On 07/16/2020 10:11 AM, lloyd wilson wrote:
I've recently acquired another controller transplant
candidate, a mid/late 80s Bridgeport 520 vmc. The old
girl uses Fanuc DC (yellow cap) axis servos and drives,
spindle is also Fanuc. I hope to keep the Fanuc servo
drives, but so far, I haven't been able to locate any
documents that spec the interface signals for the drives
(A06B-6047-H*, specifically). Can anyone point me towards
the relevant documentation?
The way Fanuc did things, they had a chip in the controller
that created a synthetic DC tachometer signal that was then
fed back to the servo amps for velocity reference. This
chip (the ST micro L290) has been unavailable for decades.
It could be done today with an FPGA and a little analog
circuitry. Some yellow cap motors actually have a DC tach
in them, you can look and see,
if it is late 80's, the servo amps are almost certainly
analog velocity servos. You need some kind of enable
signal, tach feedback and an analog velocity command
signal. And, the amps will provide some kind of fault signal.
Jon
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