Mitsubishi Electric MELSEC-LD77MS2 User Manual page 272

Storage item
Current speed
Md.27
Axis feedrate
Md.28
Speed-position switching
Md.29
control positioning movement
amount
The " " used by the positioning data currently being executed is
Command speed
Da.8
stored.

If " " is set to "-1", this area stores the command speed set
Command speed
Da.8
by the positioning data used one step earlier.

If " " is set to a value other than "-1", this area stores the
Command speed
Da.8
command speed set by the current positioning data.

When speed change function is executed, this area stores "
". (For details of change speed function, refer to Section 13.5.1.)
value
Refresh cycle: Immediate

The speed which is actually output as a command at that time in each axis is
stored. (May be different from the actual motor speed)
"0" is stored when the axis is at a stop.
Refresh cycle: Operation cycle
POINT
Refer to " "
Feedrate
Md.22

The movement amount for the position control to end after changing to position
control with the speed-position switching control is stored.
When the control method is "Reverse run: position/speed", the negative value is
stored.
Refresh cycle: Immediate
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Chapter 5 Data Used for Positioning Control
Storage details
New speed
Cd.14