Mitsubishi A1SD75P1-S3, User Manual

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8 - 4
MELSEC-A
8 ZERO POINT RETURN CONTROL
8.2 Machine zero point return
8.2.1 Outline of the machine zero point return operation
Important
Use the zero point return retry function when the zero point position is not always in
the same direction from the workpiece operation area (when the zero point is not
set near the upper or lower limit of the machine).
* The machine zero point return may not complete unless the zero point return retry
function is used.
Machine zero point return operation
In a machine zero point return, establish a machine zero point.
None of the address information stored in the AD75, PLC CPU, or servo amplifier
is used at this time. The position mechanically established after the machine zero
point return is regarded as the "zero point" to be the starting point for positioning
control.
The method for establishing a "zero point" by a machine zero point return differs
according to the method set in " Pr.45 Zero point return method".
The following shows the operation when starting a machine zero point return.
1) The machine zero point return is started.
2)
The operation starts according to the speed and direction set in the zero point return
parameters (
Pr.45
to
Pr.58
).
3)
The "zero point" is established by the method set in "
Pr.45
Zero point return method",
and the machine stops. (Refer to sections 8.2.2 to 8.2.8)
4)
If "a" is set in "
Pr.47
Zero point address", "a" will be stored as the current position in the
"
Md.29
Current feed value" and "
Md.30
Machine feed value" which are monitoring the
position.
5) "
Pr.47
Zero point address" ("a") is stored in the "
Md.43
Zero point absolute position".
6) The machine zero point return is completed.
* The " Pr.47 Zero point address" is a fixed value set by the user, but the
" Md.43 Zero point absolute position" is constantly changed by the AD75 to
indicate the "zero point", even if there is a change in the address information.
M
Zero point
Near-point dog
Machine zero point return
Fig. 8.1 Example of a machine zero point return
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