Zero Point Initialization For Auxiliary Axis; Dog-Type Reference Point Return For Auxiliary Axis - Mitsubishi Electric MELDAS C6 Instruction Manual

5. Zero Point Initialization for Auxiliary Axis

The following two methods can be used for zero point initialization for auxiliary axis.
• Method by commanding from PLC
• Method by operating on the auxiliary axis monitor screen (when the operation test mode signal
from PLC is ON)
Dog-type method conforms to the method by commanding from PLC, and dogless-type method to
the method by operating on the auxiliary axis monitor screen.

5.1 Dog-type Reference Point Return for Auxiliary Axis

The dog-type reference point return is a method for establishing the coordinate zero point in an
incremental system. The coordinate zero point is determined with the electrically determined reference
point (machine specific point) used as a reference. This reference point is determined by the signals
(near-point dog signals) turned ON/OFF by the near-point dog and limit switch.
In the motor end position detector there is a Z phase signal that is output once per rotation. Looking
from the movable section of the machine driven by the motor, a Z phase signal is output for every set
movement amount. The position at which this Z phase is output is called the grid. One specific point of
these grid points is recognized as the electrical zero point by the servo amplifier. The dog signal is
used as a means to designate/recognize which grid point is the electrical zero point in the servo
amplifier.
Electrical zero point
(1) Operation principle
The operation to determine the electrical zero point is explained below.
The dog signal is OFF when the limit switch is on the near-point dog. The dog signal is a B
contact that is ON, when the limit switch is not on the near-point dog.
(1) When the machine movable parts are
(2) When the machine movable parts are
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5. Zero Point Initialization for Auxiliary Axis
5.1 Dog-type Reference Point Return for Auxiliary Axis
→
Determined by the electrical zero
point and reference point shift
amount (ZRNshift).
The default shift amount is 0, and
the electrical zero point and
reference point are in the same
position.
moved, the dog signal limit switch is ON
according to the near-point dog, and the
dog signal is OFF.
moved further in the same direction, the
limit switch leaves the dog, and the dog
signal turns ON.
search engine
→
Reference point
Direction of machine movement
Near-point dog
Direction of machine movement
∆ ∆
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Coordinate zero point
Determined by the reference point and
the offset amount. The default offset
amount is 0, and the electrical zero
point, reference point, and coordinate
zero point are in the same position.
Limit switch
∆ ∆ ∆ ∆ ←
▲
Electrical zero point
∆ ∆
▲
Electrical zero point
Grid