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4. STARTUP
(2) How to find the cause of position shift
Positioning unit
(a) Output pulse
counter
Q
P
CMX
CDV
(C) Servo-on (SON),
stroke end
(LSP/LSN) input
(A)
(b) Cumulative command
pulses
C
Servo motor
M
Encoder
L
Machine
(d) Machine stop
position M
(B)
(c) Cumulative
feedback pulses
Servo amplifier
Electronic gear
(parameters No. PA06, PA07)
When a position shift occurs, check (a) output pulse counter, (b) cumulative command pulse display, (c)
cumulative feedback pulse display, and (d) machine stop position in the above diagram.
(A), (B) and (C) indicate position shift causes. For example, (A) indicates that noise entered the wiring between
positioning unit and servo amplifier, causing pulses to be mis-counted.
In a normal status without position shift, there are the following relationships:
1) Q P (positioning unit's output counter servo amplifier's cumulative command pulses)
2) When using the electronic gear
CMX (parameter No. PA06)
CDV (parameter No. PA07)
P
C (cumulative command pulses electronic gear cumulative feedback pulses)
3) When using parameter No. PA05 to set the number of pulses per servo motor one rotation.
262144
FBP (parameter No. PA05)
P
C
4) C
M (cumulative
feedback pulses travel per pulse machine position)
Check for a position shift in the following
sequence:
1) When Q P
Noise entered the pulse train signal wiring between positioning unit and servo amplifier, causing
pulses to be miss-counted. (Cause A)
Make the following check or take the following measures:
Check how the shielding is done.
Change the open collector system to the differential line driver system.
Run wiring away from the power circuit.
Install a data line filter. (Refer to section 12.17 (2)(a).)
2)
CMX
CDV
P
C
When
During operation, the servo-on (SON) or forward/reverse rotation stroke end was switched off or the
clear (CR) and the reset (RES) switched on. (Cause C)
If a malfunction may occur due to much noise, increase the input filter setting (parameter No. PD19).
3) When C
M
Mechanical slip occurred between the servo motor and machine. (Cause B)
Содержание MELSERVO MR-J3 A Series
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