Inverter Positioning; Feedback Control With Error Counter; Reducing Positioning Time; Features - Omron CP1L-EL20DR-D Operation Manual

Inverter Positioning

7-3 Inverter Positioning
7-3-1

Features

Feedback Control
with Error Counter
Reducing Positioning
Time
316
Positioning can be achieved using an inverter. This enables a far more eco-
nomical positioning system than with a servomotor.
A position error counter built into the CP1L-EL/EM CPU Unit enables high-
precision positioning with an Inverter using feedback control. The PULSE
OUTPUT instruction is used in the ladder program in the CP1L-EL/EM CPU
Unit to output internal pulses to a built-in error counter.
The error counter calculates the position error from the number of input inter-
nal pulses and the number of feedback pulses from the rotary encoder, and
sends speed commands to the inverter so that the position error goes to zero.
CP1L-EL/EM CPU Unit
SYSMAC
CP1L
COM 01 03 05 07 09 11
NC 00 02 04 06 08 10
POWER
RUN
ERR/ALM
Internal pulses
INH
LNK/ACT
BKUP
1
Positioning
00 01 02 03 04
ANALOG INPUT
COM(V+) COM 05
instruction
V1 + V2 + COM
MAC Address:
01234567890A
With traditional inverter positioning, positioning patterns are created in which
set positions are detected to trigger changes in the speed. Pulses are read
from the encoder and compared to set values during positioning to enable
determining when a position requiring a speed change has been reached.
This results in positioning errors at speed-change points when stopping at
high speed, reducing stopping precision. To ensure high-precision positioning,
sufficient deceleration was required before stopping, but this increases the
positioning time.
With the CP1L-EL/EM's inverter positioning function, feedback pulses are
used so that the prevent position is always known, increasing positioning
accuracy. And because preset positioning patterns are used for deceleration
and stopping, positioning time is reduced.
Ladder program
01 03 05 07 09 11
00 02 04 06 08 10
Speed command
Error
counter
RS-485 or analog output
2
06 00 01 03 04 06
07 COM 02 COM 05 07
Feedback pulses
Section 7-3
PLS2 instruction
Inverter
Frequency
command
Encoder
Motor