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8  CONTROL SUB FUNCTIONS
8.4  Functions to Limit the Control
Control details
The following drawing shows the operation of the torque limit function.
■RD77MS4 operation example
*1 The torque limit setting value or torque output setting value becomes effective at the PLC READY signal [Y0] rising edge (however, after 
the servo turned ON.)
If the torque output setting value is "0" or larger than the torque limit setting value, the torque limit setting value will be its value.
*2 The torque limit setting value or torque output setting value becomes effective at the positioning start signal [Y10] rising edge.
If the torque output setting value is "0" or larger than the torque limit setting value, the torque limit setting value will be its value.
*3 The torque change value is cleared to "0" at the positioning start signal [Y10] rising edge.
Precautions during control
 • When limiting the torque at the "[Pr.17] Torque limit setting value", confirm that "[Cd.22] New torque value/forward new 
torque value" or "[Cd.113] Reverse new torque value" is set to "0". If this parameter is set to a value besides "0", the setting 
value will be validated, and the torque will be limited at that value. (Refer to Page 259 Torque change function for 
details about the "new torque value".)
 • When the "[Pr.54] Home position return torque limit value" exceeds the "[Pr.17] Torque limit setting value", the error "Home 
position return torque limit value error" (error code: 1B0DH, 1B0EH) occurs.
 • When the operation is stopped by torque limiting, the droop pulse will remain in the deviation counter. If the load torque is 
eliminated, operation for the amount of droop pulses will be carried out. Note that the movement might start suddenly as 
soon as the load torque is eliminated.
Each operation
PLC READY signal [Y0]
All axis servo ON [Y1]
Positioning start signal 
[Y10]
*1 *1
300 250
*2 *2 *2
100 1500
*3 *3 *3
0
0 300 300 100 150 150
0
(Forward/reverse torque limit value same setting)
[Cd.112] Torque change function 
switching request
[Cd.22] New torque value/forward 
new torque value
[Md.35] Torque limit stored 
value/forward torque limit 
stored value
[Cd.101] Torque output setting 
value
[Pr.17] Torque limit setting value