Absolute Encoders With 24-Bit Resolution; Encoder With 24-Bit Resolution And Electronic Gear Ratio Settings - YASKAWA SVC User Manual

5.4

Absolute Encoders with 24-Bit Resolution

Encoders with 24-bit resolutions can be used with
use an encoder with a 24-bit resolution, it may not be possible to specify correct travel dis-
tances and deceleration times with the MP3000.
This section describes settings and precautions when using a 24-bit encoder.
Also, if you write any fixed parameters after turning ON the power supply, save the settings to
flash memory and then turn the power supply OFF and ON again.
5.4.1 Encoder with 24-Bit Resolution and Electronic Gear
Ratio Settings
The setting of OL
the travel distance that you can specify from the MP3000 can be from -2,147,483,648 to
+2,147,483,647 reference units.
There are 16,777,216 pulses per motor rotation of the 24-bit resolution absolute encoder.
Therefore, depending on the machine, the distance that can be traveled may not be sufficient.
The deceleration time during deceleration may also be restricted. Refer to the following section
for details.
5.4.3 Possible Travel Distances and Deceleration Times for the MP3000 on page 5-55
To eliminate this problem, set the electronic gear ratio in the SERVOPACK parameters to 16:1
to use the 24-bit resolution encoder as a 20-bit resolution encoder.
The relation between the electronic gear ratio in the SERVOPACK parameters and the number
of reference pulses in the MP3000 is shown in the following figure.
Electronic Gear
Ratio in the SER-
VOPACK Param-
eters
16:1
(Equivalent to
20 bits.)

5.4.1 Encoder with 24-Bit Resolution and Electronic Gear Ratio Settings


1C (Position Reference Setting) in the MP3000 is two words. Therefore,
MP3000
MECHATROLINK-III
Reference unit selection = mm
Travel distance per machine rotation = 10,000 reference units
Servomotor gear ratio = 1
Machine Gear Ratio Term = 1
Number of pulses per motor rotation = 1,048,576
If a movement of 10,000 reference units is
commanded, 1,048,576 pulses will be output.

5.4 Absolute Encoders with 24-Bit Resolution

Σ
-7-Series SERVOPACKs. However, if you
Operation
Σ
-7
Motor
Pn20E = 16
Pn210 = 1
Use a 24-bit absolute encoder.
The motor will rotate one rotation for a
command of 1,048,576 servo reference units.
Continued on next page.
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