Mitsubishi Electric FR-A700 Technical Manual page 284

2.11.8 Troubleshooting (position control)
Case
1 Motor does not rotate
2 Position shift occurs.
3 Motor or machine hunts.
Machine operation is
4
unstable
Cause
(1) The phase sequence of the motor
or encoder wiring is wrong.
(2) [Pr. 800 The control mode selection]
setting is improper.
(3) The servo ON signal or stroke end
signal (STF, STR) is not input.
(4) Command pulse, position pulse
sign (NP) are not correctly input.
(5) The [Pr. 419 Position command
source selection] setting is not
correct.
(6) When the [Pr. 419 Position
command source selection] setting
is 0, the position feed amount [Pr.
465 to Pr. 494] settings are not
correct.
(1) The command pulses are not
input correctly.
(2) The command is affected by noise
or the encoder feedback signal is
compounded with noise.
(1) The position loop gain is high.
(2) The speed loop gain is high.
(1) The acceleration/deceleration
time setting has adverse effect.
A700
(A700)
(1) Check the wiring (Refer to page 86)
(2) Check the [Pr. 800] setting. (Refer to page 252)
(3) Check that the signals are input correctly.
(4)-1 Check that the command pulses are input correctly.
(Check the cumulative command pulse value in [Pr. 430])
(4)-2 Check the command pulse form and [Pr. 428 Command
pulse selection] setting.
(4)-3 Check that the position pulse sign (NP) is assigned to
the input terminal. (inverter pulse input)
(5) Check the [Pr. 419 Position command source selection].
(6) Check the position feed amount in [
(1)-1 Check the command pulse form and [Pr. 428 Command
pulse selection] setting.
(1)-2 Check that the command pulses are input correctly.
(Check the cumulative command pulse value in [Pr. 430])
(1)-3 Check that the position pulse sign (NP) is assigned to
the input terminal. (inverter pulse input)
(2)-1 Decrease [Pr. 72 PWM frequency selection].
(2)-2 Change the earthing (grounding) point of shielded wire.
Or leave the cable suspended.
(1) Decrease [Pr. 422].
(2)-1 Perform easy gain tuning.
(2)-2 Decrease [Pr. 820] and increase [Pr. 821] .
(1) Decrease the [Pr. 7, Pr. 8] value.
318
PARAMETER
Countermeasures
Pr. 465 to Pr. 494
].