Peter C. Wallace wrote: > The AD650 has bipolar output but not quadrature input so would probably not > be > useful as a bidirectional tachmometer replacement. > A quadrature to direction pulse converter would be a very simple circuit to make. > The L290 interestingly enough is a sine/cosine quadrature input device, > probably emulated easily with a DSPIC if needed. > I think it will work fine with a digital input signal, too, if it were only still available. > On the other hand if the velocity estimation from the encoder counter is good > enough, why not drop all the external futzy whatziz and do all the PID loop > in > EMC... > Yes, some people have advocated that, switch the servo amps to torque mode, and use PID2. > Do the Fanuc drives need a analog velocity signal? That is, is their > encoder/velocity feedback not built into the drives themselves? > Yes, the typical Fanuc servo amp, from way back to relatively recently, were run in velocity servo mode, and a component of the control converted the encoders to velocity signals to give the amps the velocity feedback. It is possible to convert even old Fanuc amps to torque mode, but it requires moving wires and components on the board to bypass the velocity error amp. They do not take encoder signals, just enable, velocity command and tachometer.
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