Mitsubishi Electric RD77MS2 - Page 221

8 CONTROL SUB FUNCTIONS
8.2 Sub Functions Specifically for Machine Home Position Return
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8
■Setting the dwell time during a home position return retry
The home position return retry function can perform such function as the dwell time using "[Pr.57] Dwell time during home
position return retry" when the reverse run operation is carried out due to detection by the limit signal for upper and lower
limits and when the machine home position return is executed after the near point dog is turned OFF to stop the operation.
"[Pr.57] Dwell time during home position return retry" is validated when the operation stops at the "A" and "B" positions in the
following drawing. (The dwell time is the same value at both positions "A" and "B".)
Precaution during control
• The following table shows whether the home position return retry function may be executed by the "[Pr.43] Home position
return method".
• Always establish upper/lower limit switches at the upper/lower limit positions of the machine. If the home position return
retry function is used without hardware stroke limit switches, the motor will continue rotation until a hardware stroke limit
signal is detected.
• Do not configure a system so that the servo amplifier power turns OFF by the upper/lower limit switches. If the servo
amplifier power is turned OFF, the home position return retry cannot be carried out.
• The operation decelerates upon detection of the hardware limit signal, and the movement starts in the opposite direction. In
this case, however, the error "Hardware stroke limit (+)" (error code: 1904H, 1905H) or "Hardware stroke limit (-)" (error
code: 1906H, 1907H) does not occur.
The settings of the upper/lower stroke limit signal are shown below. The home position return retry function
can be used with either setting. (Page 243 Hardware stroke limit function)
• External input signal of Simple Motion module
• External input signal of servo amplifier
• External input signal via CPU (buffer memory of Simple Motion module)
[Pr.43] Home position return method Execution status of home position return retry function
Near-point dog method : Execution possible
Count method 1 : Execution possible
Count method 2 : Execution possible
Data set method 
Scale origin signal detection method : Execution not possible
B
Near-point dog
Zero signal
Stop by near-point dog OFF
Stop by limit signal detection
A
Limit signal OFF
Hardware limit switch
Home position
[Pr.44] Home position
return direction
Machine home position
return executed again
Machine home position
return start
Reverse run operation after
limit signal detection