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8 ZERO POINT RETURN CONTROL
8.1 Outline of zero point return control
8.1.1 Three types of zero point return control
In "zero point return control" a position is established as the starting point (or "zero
point") when carrying out positioning control, and positioning is carried out toward that
starting point.
It is used to return a machine system at any position other than the zero point to the
zero point, such as, when the D75P2 issues a "zero point return request"*, after a
positioning stop, etc.
In the D75P2, the three types of controls shown below are defined as "zero point return
control", following the flow of the zero point return work.
Any of these three zero point return control types can be executed by setting the "zero
point return parameters", setting "positioning start No. 9001" or "positioning start No.
9002" prepared beforehand in the D75P2 to the remote register (axis 1: RWwm, axis 2:
RWwm+8), and turning ON the positioning start signal.
(1) Establish a positioning control zero point
– "Machine zero point return" (positioning start No. 9001)
(2) Set the current stop position as the zero point.
– "Data setting method zero point return" (positioning start No. 9901)
(3) Carry out positioning toward the zero point
– "High-speed zero point return" (positioning start No. 9002).
* The "machine zero point return" in (1) above must always be carried out before
executing the "high-speed zero point return" in (3).
REMARK
Zero point return request *
The "zero point return request flag" (RX(n+1)F, RX(n+4)F) must be turned ON in
the D75P2, and a machine point return must be executed in the following cases.
At the ON
OFF of the drive unit READY signal (RX(n+1)2, RX(n+4)2).
At the OFF
ON of the remote station READY signal [RX(n+7)B]
The address information stored in the D75P2 cannot be guaranteed while the "zero
point return request flag" is ON.
The "zero point return request flag" turns OFF and the "zero point return complete
flag" (RX(n+2)0, RX(n+5)0) turns ON if the machine zero point return is executed
and is completed normally.
8 - 2
MELSEC-A
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