SD710 Series Servo Drive User Manual Chapter 5 Commissioning and Operation
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5.3.2 Soft Start
The soft start function is a speed command that converts a step speed command into a smoother constant acceleration
and deceleration. The acceleration time and deceleration time can be set, and this function is used when smooth speed
control is desired during speed control.
Related function codes
Fn. No
Parameter
Range
Default
Unit
Pn310
Soft start acceleration time (ACC) during
speed control mode
0 to 10,000
200
ms
Pn311
Soft start deceleration time (DEC) during
speed control mode
0 to 10,000
200
ms
Pn30A is the time it takes for the motor to reach the maximum speed of the motor from a stop; Pn30B is the time it
takes for the motor to reach the motor stop from the maximum speed. The actual acceleration and deceleration times
are calculated by the following equation.
Actual acceleration time =
target speed
𝑚𝑎𝑥𝑖𝑚𝑢𝑚 𝑠𝑝𝑒𝑒𝑑
× soft start (acceleration time Pn310)
Actual deceleration time =
target speed
maximum speed
× soft start(deceleration time Pn311)
Target speed
ACC
time
DEC
time
Pn310
Pn311
Maximum speed
Figure 5.24 Soft start acceleration and deceleration time effect demonstration
5.3.3 Zero speed clamp function
The zero speed clamp function is a function that performs servo lock when the speed command is below the zero
speed fixed speed threshold (Pn313) in the zero speed clamp (/ZCLAMP) ON state. In this case, a position loop is
formed inside the servo unit and the speed command will be ignored. The servo motor is fixed within ± 1 pulse of the
zero position fixed effective position, and returns to the zero position fixed position even if rotation occurs due to an
external force.
(1) Configuration of zero-speed clamp
Related function codes
Fn. No
Parameter
Range
Default
Unit
Pn313
Zero speed fixed speed threshold
0 to 10,000
10
rpm
Related input terminals