Current Position Retention Function - Mitsubishi Electric 800 Series Instruction Manual (Function

7.7

Current position retention function

Vector Vector Vector
If the operation stops with the motor shaft fixed by the electromagnetic brake or the like under position control, holding the
current position data at the output shutoff enables the operation without performing the home position return at restart.
Pr.
538 Current position retention
B015 selection
• Set Pr.538 Current position retention selection to select the combination of the position data (position command,
current position, and droop pulse) to be held. Set Pr.538 while the inverter is stopped.
• When the Pre-excitation/servo ON (LX) signal is turned OFF, the position data selected by Pr.538 and the Home position
return completed (ZP) signal are held.
• When Pr.538 = "11 or 12", the position data and the ZP signal are held also after power reset or inverter reset after the
turning OFF the LX signal.
Pr.538 setting
9999 (initial value)
1
2
11
12
*1 Cleared at power-OFF or inverter reset.
NOTE
• Do not use the current position retention function if the motor shaft is not fixed by the electromagnetic brake or the like while
the inverter output is shut off. Motor shaft rotation causes a position fault.
• Even when the motor shaft is fixed, do not use the function if the motor shaft is rotated by an external force. Motor shaft rotation
causes a position fault.
• Turn the LX signal OFF after the motor stops and servo lock is activated.
• The held position data and the Home position return completed (ZP) signal are cleared in any of the following cases:
The Pr.538 setting is changed.
The setting of electronic gear (settings of Pr.420 and Pr.421) is changed.
The main circuit capacitor life is measured.
Operation is switched between the first and second motors.
The control method is changed.
An inverter protective function has been activated.
The current position retention function is not available.
The power is turned OFF or the inverter is reset while Pr.538 = "1 or 2".
• When Pr.538 = "11 or 12", about one second is required to complete writing position data after the LX signal is turned OFF.
Do not turn OFF the power and do not perform the inverter reset during the writing of position data. If the writing is failed due
to power-OFF or inverter reset, the protective function E.OD is activated when the power is turned ON.
• If the inverter output is frequently shut off during the position control operation, do not set "11 or 12" in Pr.538. The frequent
shutoff while Pr.538 = "11 or 12" will shorten the life of the EEPROM.
• When Pr.538 = "11 or 12", position data from -2147483648 to 2147483647 can be stored in EEPROM. When a position data
is out of the range, the data is not stored in EEPROM, and the previous data is cleared.
• To give a command to the inverter via communication, use the current position retention function with Pr.800 = "3". When
Pr.800 = "4" (speed/position switchover) or "5" (position/torque switchover), the held position data and ZP signal may be
cleared since the same control mode as when the MC signal is OFF is performed regardless of the actual signal state until the
inverter power is turned ON and the communication is established.
182
7. Position Control
7.7 Current position retention function
Name Initial value
9999
Position data
Position command Current position
Cleared Cleared
Aligned with current
*1
Held
*1
position
*1 *1
Held Held
Aligned with current
Held
position
Held Held
Setting
range
1, 2, 11, 12 Select the combination of the position data to be held.
9999 Function disabled
Droop pulse
Cleared
Cleared
*1
Held
Cleared
Held
Description
Storing data in
ZP signal
EEPROM
Turned OFF Disabled
*1
Disabled
Held
Disabled
*1
Held
Enabled
Held
Held Enabled