Mitsubishi Electric MELSEC iQ-R RD75P4, User Manual

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7 CONTROL SUB FUNCTIONS
7.4 Function to Limit Control
Torque limit function
If the torque generated in the servo motor exceeds Torque limit value, this function limits the generated torque to a value
within the setting range of Torque limit value.
This function protects the reducer and limits the power of the pressing operation against the stopper. This function controls the
operation so that an excessive load or excessive force is not applied to the machine.
The RD75 does not perform the torque limit of the servo motor directly using this function. The torque limit command to the
servo amplifier is performed by the D/A converter module.
System configuration for performing the torque limit
Perform the torque limit in the following configuration. (The following modules are required.)
• D/A converter module
• Drive unit capable of performing the torque limit control with the analog voltage input
The RD75 monitors the creep speed reach during the OPR control and updates the value in [Md.35] Torque
limit stored value to the one in [Pr.54] OPR torque limit value. Monitoring this value prevents the need to
monitor the creep speed reach using the program. If all controls of the torque limit value are performed using
the program ((1) Read with the FROM instruction in the figure), this function does not have to be used.
(1) Read the value in [Md.35] Torque limit stored value.
(2) Write the read value into the D/A converter module. (The value must be converted according to the specifications of the D/A converter module.)
(3) The drive unit performs the torque limit according to the voltage input value from the D/A converter module.
CPU module RD75 Drive unit
Positioning control
(3) Torque limit
(1)
(2)
D/A converter module
Torque limit
stored value
Buffer memory
Md.35
Read with
the FROM
instruction
Write with the
TO instruction