Yaskawa MP920 Motion Module - Manual (Page 81)

2.4 Position Control Using Motion Commands
2-55
2
Ladder Logic Program Example
Fig. 2.18 External Positioning Programming Example (DWG H03)
The example in the above illustration has been greatly simplified. In actual operation, each
register can be controlled from the user program.
2.4.4 Zero Point Return (ZRET)
„ Overview
The zero point return operation is used to return to the machine coordinate system zero
point.
The machine coordinate system zero point position data is destroyed when the power is
turned OFF. Therefore, after turning ON the power, the machine coordinate system zero
point must be repositioned. In general, a zero point pulse (Phase-C pulse) and a limit switch
showing the zero point area are used to determine the zero point.
There are two zero point return methods. One method uses motion commands, and the other
method uses the zero return mode. Care is required because zero point return operations are
different with these two methods.
The method of using motion commands is described below.
IFON
H0104
RUNMOD
OWC000
0000010000
EXMDIST
OLC024
RUN
OBC0010
SB000004
2
MCMDCODE
OWC020
IEND
DEND
RUNPB
IB00304
0001000000
XREF
OLC012
Set the position control mode to ON.
Driver operation command (RUN)
Execute external positioning (EX_POSING)
as the motion command.
When IB00304 turns ON, position control
starts, and the axis moves to absolute position
1000000. When a latch signal (external
positioning signal) is input while the feed
operation is executing, the axis travels only the
external positioning travel distance (10,000
pulses). When travel is completed, the
IBC000D positioning completed signal turns
ON. If a latch signal has not been input, the
IBC00D positioning completed signal turns
ON when absolute position 10000 is reached.
Position reference pulse (XREF)
(Absolute position: 10000)
External positioning travel distance
(EXMDIST)