4.2 Setup Procedure
4.2.2 Setting the Multiturn Limit
4-4
4.2.2
Setting the Multiturn Limit
When you use an absolute encoder, set the multiturn limit to match the rotational coordinate
system that is used by the system.
When you use a rotational coordinate system, you must set the multiturn limit.
Refer to the following manual for details on setting the multiturn limit.
Σ
-7-Series
Σ
-7S SERVOPACK with MECHATROLINK-III Communications References Product Manual (Manual No.:
SIEP S800001 28)
Note: Turn the power supply OFF and ON again, or send the Setup Device command (CONFIG) from the host con-
troller to enable changes to these parameters.
4.2.3
Absolute Encoder Origin Offset
If you use an absolute encoder, you can set Pn808 (Absolute Encoder Origin Offset) to the off-
set between the encoder position and the machine coordinate system position (feedback posi-
tion (APOS)).
An example of when the encoder position (X) is at the origin of the machine coordinate system
(0) is provided below.
To set encoder position (X) at the origin of the machine coordinate system (0), the following
relationship must exist in the parameter settings: Pn87C
≤
Pn808
≤
Pn87A.
Pn808 is set as follows:
•
If the offset is smaller than the setting of Pn87C (First Rotational Coordinate): Pn808 = Offset
+ (Pn87A
−
Pn87C + 1)
Pn205
Multiturn Limit
Setting Range
Setting Unit
Default Setting
When Enabled
Classification
0 to 65,535
1 rev
65535
After restart
Setup
24 (PnA48)
Multiturn Limit Setting
Setting Range
Setting Unit
Default Setting
When Enabled
Classification
0 to 65,535
1 rev
65535
After restart
Setup
Setting Example for the Multiturn Limit (Pn205)
Conditions: A turntable is controlled with rotational coordinates where one revolution equals
360°, which is equal to 36,000 reference units.
First rotational coordinate (Pn87C): 0
Last rotational coordinate (Pn87A): 35,999
Gear ratio: 1/100
The electronic gear ratio is as follows:
=
=
With this gear ratio, the motor will turn 100 times for 1 revolution of the turntable. The Multi-
turn Limit (Pn205) is therefore 99 (100
−
1 = 99).
If the multiturn limit is not set to match the machine rotational coordinate system, the position
may become offset.
Example
Turntable
Load
s
haft
Gear
Encoder: 20 bit
s
Motor
Gear ratio: 1/100
B
A
Pn20E
Pn21
104,857,600
36,000
Important
