Re: [CAD_CAM_EDM_DRO] Out of Estop.. BUT

imranjawaid@... wrote:

> I've only one axis hooked up with the computer
> for now.It is something like this:
>
> Regenerative Resistor
> |
> STG2 --> AC AMP-->Thermal Relay--> AC Servo Motor w/ encoder
>
> Thermal relay is not connected with GND
>
> Now few more problems turned out.
> 1)Motor rotates very slightly in a jerky motion simultaneously
> giving a high pitched sound. I tried the zero setting on
> the amplifier drive. It helps to slow down the motion but
> didn't removed it completly.

Well, the jerky motion is strange. How does this amp get velocity
feedback? Does it take the encoder signals, or is there a tach?

> I think thermal relay has something to do with it.
> I'm not sure of Thermal relay function.

The regenerating resistor is to absorb energy when the motor is being
slowed by the amp, and energy flows from the motor to the amp.
At first, the amp just puts the energy back into the DC storage
capacitor,
but when the voltage becomes too high, energy is dumped into the
resistor. If the resistor overheats, it shuts down the amp to prevent
the resistor from burning up.

> I ran EMC , X axis keeps ticking in EMC
> I got Machine ON and it gave me the following error message
> "Error:Axis 0 following error"

The ticking seems to be a design problem either in the LS7266 chips
or the Servo-to-Go card. On occasion, the encoder readout function
either gets bytes mixed up, or the bytes are being read without the
24-bit latch having taken a clean sample of all the bytes. This problem

shows up most when the encoder is reporting numbers very close to
zero, which is the pattern it takes when EMC is started. The transition

across zero requires a carry (or borrow) across 23 of the 24 bits, and
if they use a ripple carry, it can take a long time. It may be that
with
the clock rate used in the STG card, it doesn't allow enough time for
these carrys to complete. I have the same problem with my original
version of the STG card. If you move the encoder a small amount away
from the position at power up, you won't see this 'clicking'.

>
> 2)I stopped the motor supply but kept the
> encoder running.I started EMC , got machine ON.
> First i rotated the motor shaft slowly by hand
> (on which the encoder is mounted) , EMC started giving me the
> encoder ticks on X-Axis.But after I increased the rotation speed
> slightly
> the encoder reading stopped.

Others have reported behavior like this. I don't know what it means.
On my system, the encoder reads correctly at all speeds. But, in the
machine on state, it expects closed loop control, and will give a
following error fault when you move it farther than the error bound.
You will get a little dialog box somewhere on the screen, and it
has to be OK'd before you can do much. But, I think the axis displays
SHOULD update, even before the dialog box has been OK'd.

Jon