Inverter Positioning; Features - Omron CP1L Operation Manual

Inverter Positioning

5-3 Inverter Positioning
5-3-1

Features

Feedback Control
with Error Counter
Reducing Positioning
Time
280
Simple, accurate high-speed positioning can be achieved using an inverter.
This enables a far more economical positioning system than with a servomo-
tor.
A position error counter built into the CP1L 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 CPU Unit to output inter-
nal 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 CPU Unit
SYSMAC
IN
CP1L
L1 L2/N COM 01 03 05 07 09
00 02 04 06 08
Internal pulses
Positioning
00 01 02 03
COM COM COM COM
instruction
OUT
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'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 stop-
ping, positioning time is reduced.
11 01 03 05 07 09 11
10 00 02 04 06 08 10
Speed command
Error
counter
RS-485 or analog output
04 06 00 01 03 04 06
05 07 COM 02 COM 05 07
Feedback pulses
Section 5-3
Ladder program
PLS2 instruction
Inverter
Encoder
Frequency
command
Motor