Pre-Reading Start Function - Mitsubishi Electric MELSEC-LD77MS2 User Manual

13.7.7 Pre-reading start function

[LD77MS4 operation example]
V
Positioning start signal
[Y10,Y11,Y12,Y13]
Execution prohibition flag
[Y14,Y15,Y16,Y17]
BUSY signal
[XC,XD,XE,XF]
Md. 26 Axis operation
status
The "pre-reading start function" does not start servo while the execution prohibition flag
is ON if a positioning start request is given with the execution prohibition flag ON, and
starts servo within operation cycle after OFF of the execution prohibition flag is
detected. The positioning start request is given when the axis is in a standby status,
and the execution prohibition flag is turned OFF at the axis operating timing.
The "pre-reading start function" will be explained below.
[1] Controls
[2] Precautions during control
[3] Program examples
[1] Controls
The pre-reading start function is performed by turning ON the positioning start
signal with the execution prohibition flag ON, or by executing the dedicated
instruction (ZP.PSTRT1, ZP.PSTRT2, ZP.PSTRT3, and ZP.PSTRT4). However,
if positioning is started with the execution prohibition flag ON, the positioning data
is analyzed but servo start is not provided. While the execution prohibition flag is
ON, "
Axis operation status
Md.26
servo starts within operation cycle after the execution prohibition flag has turned
OFF, and "
Md.26
speed control) that matches the control method. (Refer to Fig.13.46)
Signal
Execution prohibition flag
ON
OFF
ON
OFF
ON
OFF
Position control Standby
Fig. 13.46 Operations of pre-reading start function
" remains unchanged from "5: Analyzing". The
" changes to the status (e.g. position control,
Axis operation status
LD77MS2/LD77MS4
Y14, Y15, Y16, Y17
Positioning start timing
Ta
Positioning data
Execution prohibition flag OFF waiting
analysis
Analyzing
(Note): Refer to Section 3.3 for input/output signal of LD77MS16.
13 - 91
Chapter 13 Control Sub Functions
LD77MS16
Execution prohibition flag
Cd.183
Operation cycle or less
t
Position control