7 Before Starting Positioning Operation
114
FX
3U
-20SSC-H Positioning Block User's Manual
7.9 Other functions
7.9.4
Absolute position detection system
An absolute position detection system is available with the 20SSC-H.
→
For the parameters, control data and monitor data, refer to Chapter 11
What is the absolute position detection system?
In the absolute position detection system, the current position is stored in the servo amplifiers battery backed
memory, and even if the work piece moves at power failure, the moving distance is added to the current
position with the absolute encoder and servo amplifier absolute position system. After power-ON, the
absolute position detection system does not require the zero return procedure.
Caution
When the absolute current position from the zero-point exceeds the range of 32 bit data (-2,147,483,648 to
2,147,483,647), the current value overflow flag in the status information is ON and an error (error code: 3004)
occurs at the time of next power supply starting.
Note
• The 20SSC-H Ver. 1.30 or later supports unlimited length feed in ring operation when the absolute position
detection system is used. (The error in the above caution does not occur in this case.)
However, the reciprocal movement instruction does not support unlimited length feed in ring operation
when the absolute position detection system is used.
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For ring operation, refer to Section 7.8
• When zero return operation is performed using the absolute position detection system, the zero point
information is saved in the flash memory in the 20SSC-H.
At this time, the number of writes to the flash memory (Maximum allowable number of writes: 100,000) is
increased by "1."
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For the number of writes to the flash memory, refer to Subsection 11.3.34
1. Conditions to use the absolute position detection system
• Use servomotors with absolute position encoders.
• Use a backup battery with the servo amplifier.
• Enable the absolute position detection system in the servo parameters.
2. Initial zero-point determination
Even with the absolute position detection system, the zero-point must be determined at least once after the
equipment is manufactured.
To determine the zero-point for the first time, perform zero return according to one of the following types
: data set type, DOG type or stopper type.
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For zero return operation, refer to Section 8.1
BFM Number
Description
X-axis
Y-axis
Absolute position
detection system
BFM #15003
BFM #15203
Select whether or not to use the absolute position detection system.
0: Disable (use in incremental system)
1: Enable (use in absolute position detection system)
CAUTION
A parameter error occurs if you select "1: Enable (use in absolute position
detection system)" when using the increment synchronous encoder.
Absolute position detection system setting
0
0
0
