MITSUBISHI ELECTRIC MOTION CONTROLLERS Q172DCPU - Manual (Page 124)

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4 AUXILIARY AND APPLIED FUNCTIONS
4.8 Monitor Function of the Main Cycle
(1) Information for main cycle of the Motion CPU (process cycle executed at free time
except for motion control) is stored to the special register.
(2) Since the automatic refresh of CPU shared memory and normal task of Motion
SFC program are executed in the main cycle, make it reference for process time,
etc. to program.
(3) There are following methods to shorten a main cycle.
(a) Lengthen an operation cycle setting.
(b) Reduce the number of event task programs to execute in the Motion SFC
program.
(c) Reduce the number of normal task programs to execute simultaneously in
the Motion SFC program.
(d) Reduce the number of automatic refresh points of CPU shared memory.
(4) When a main cycle is lengthened (more than 1.0[s]), a WDT error may occur in
the Motion CPU.
(5) Details of main cycle monitor register is shown below.
No. Name Meaning Details
SD520 Scan time
Current scan time
(1ms units) • Current scan time is stored in the unit 1[ms].
• Setting range (0 to 65535[ms])
SD521 Maximum scan time
Maximum scan time
(1ms units) • Maximum main cycle is stored in the unit 1[ms].
• Setting range (0 to 65535[ms])