Mitsubishi Electric MELDAS C6 Instruction Manual page 358

(2) Reference point
The reference point is the point positioned to when the dog-type reference point return is
executed. Note that a separate setting method is used for the absolute position detection.
The reference point is the point positioned to with the manual reference point return and G28
command in the machining program.
Using parameters, the reference point can be shifted from the electrical zero point position.
(3) Grid point
The position detector has a Z-phase that generates one pulse per rotation. The 0-point position
of this Z-phase is the grid point. Thus, there is a grid point per rotation of the position detector,
and the machine has many grid points at a set pitch.
The grid point can be set per grid space by setting the grid space (SETUP PARAM. #2029
grspc). Thus, multiple grid points can be set per detector rotation.
(4) Grid space
The distance between the grid points is the grid space. The grid space can be set in mm units
with the SETUP PARAM. #2029 grspc.
(5) Grid amount
The grid amount expresses the distance from when the near-point detection limit switch leaves
the near-point dog and reaches the grid point (electrical zero point) when the dog-type reference
point return is executed.
The grid amount can be confirmed with "GRID" on the "ALM/DIAG" "SERVO MONITOR (2)"
screen of the setting and display unit.
After setting the grid mask, the grid amount shows the distance from the grid mask OFF to the
grid point.
(6) Basic machine coordinate system zero point
The basic machine coordinate system is a coordinate system that expresses a position decided
characteristically for the machine.
The following positions are expressed with the machine coordinate system.
• No. 1 to No. 4 reference point position
• Workpiece coordinate system zero point position
• Stored stroke end position
• Soft limit position
• Chuck barrier position
Usually, the machine coordinate zero point position is the same as the reference point position,
but it can be shifted with the parameters.
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3. Adjustment of Dog-type Reference Point Return
3.2 Dog-type Reference Point Return
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