L7C Series AC Servo Drives Quick Start Guide
Page 32 of 60
L7C Servo Drives Quick Start Guide – 1st Ed. Rev A, 11/29/2021
Step 5: Set Electronic Gear Ratio
Index Mode S
tep 5
Substep
Task
A
On the Electronic Gear Ratio screen, keep the
Electric Gear Mode
selection set to
Use Electric Gear 1~4
B
Set the desired gear ratio for Egear 1 (note that Index Position Mode ONLY uses Electric Gear 1)
If no gear ratios are changed (all numerators and denominators have default values=1), then a position
command of 131072 user units (UU) will result in one motor shaft revolution This is because the LS
APMC servo motors sold by Automation Direct have 17 bit serial encoders (17 bits=131072 pulses/rev)
To convert this into an easier number to use for positioning adjust the Electronic Gear ratios in step C
C
If desired, set the Electronic Gear ratio so that one motor revolution = 360 user units (360 user units/rev
will be used later in the Index example)
To do this, set the Electronic Gear numerator to the 17-bit encoder value (encoder pulses per motor rev)
and set the denominator to your desired User Units/rev
• Set Electronic Gear Numerator 1 (0x300C) = 131072 (encoder pulses per motor rev)
• Set Electronic Gear Denominator 1 (0x3010) = 360 (user units per motor rev)
Now all Index positions, speeds, accelerations, and decelerations will be referenced in degrees
Actual Move Distance = 720 user units x 131072 encoder pulses
motor rev
x 1 motor rev
360 user units
= 2 x 131072 encoder pulses
(which is 2 motor revs)
NOTE:
You will probably want more resolution than 360 user units per motor rev The basic rule of thumb
is:
• Set Electronic Gear Numerator 1 = 131072
• Set Electronic Gear Denominator 1 = your desired pulses per motor rev
D
[This is located on the same screen with Electronic Gear Ratio]
Configure the Encoder Output signal if desired If the definition isn’t known, the Encoder Output can be
configured later with Encoder Output Pulse (0x3006) and Encoder Output Mode (0x3007) on the Object
Dictionary \ Index tab
E
Click
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