User Manual Of EL7-EC** AC Servo
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4.2 Electronic gear ratio
When loaded axis moved for 1 command unit, it corresponds to motor encoder unit which
is converted in more comprehensible physical units such as μm. The use of electronic
gear ratio is to turn the movement in physical units to required pulse count equivalency.
Electronic gear ratio =
Rotor movement (Encoder unit)
Loaded axis movement(Command unit)
Rotor might be connected to load through reducer or other mechanical structures.
Hence, the gear ratio is closely related to reducer gear ratio, position encoder resolution
and mechanical dimensions related parameters.
Electronic gear ratio =
Encoder resolution
Loaded axis resolution
Electronic gear can be set through Pr0.08. If Pr0.08
≠
0, Pr0.08 is valid. If Pr0.08 = 0,
object dictionary 6092-01 is valid.
Command pulse count per motor revolution needs to be
≥
Encoder Pulse Count per
Revolution / 8000.
EL7-EC series comes with motors with 23-bit encoder. Pulse count per revolution for
23-bit encoder = 8388608. From the condition above, the command pulse count per
motor revolution for 23-bit encoder
≥
1049.
Pr0.08
Name
Command pulse counts
per revolution
Mode
F
Range
0~838860
8
Uni
t
P-
Default
0
Index
2008h
Activation
After restart
Pulses per revolution can be set using object dictionary 608F, 6091, 6092. However, Pr0.08 has
higher priority.
Index
608Fh-01
Name
Encoder resolution
Unit Encoder unit Structure
VAR
Type
UInt 32
Access
R
0
Mapping
TPDO Mode F
Range
1~2147
48364
7
Default 0
To set encoder resolution
Index
6091h-01
Name
Electronic gear ratio
numerator
Unit
r
Structure
VAR
Type
Dint 32
Access
RW
Mapping RPDO Mode
F
Range
1-21474
83647
Defaul
t
1
To set electronic gear ratio numerator
