Mitsubishi Electric MELSEC-LD77MS2 User Manual page 737

[LD77MS4 program example]
External command
valid signal
(3) Add the following sequence program to the control program, and write it to
the PLC CPU.
Write 1000000 to D108 and D109.
Input the external command signal.
DTOP H0 K1514 D108 K1
K62 K1
TOP H0 K1
TOP H0 K1505 K1 K1
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Chapter 13 Control Sub Functions
[Speed change processing]
<Write the new speed. >
<Set the external command function
selection to external speed change
request. >
<Set the external command signal input
to valid.>
(LD77MS starts speed change processing.)