10.3 Using an Absolute Encoder
10-21
10
(6) Ladder Program for Infinite Length Axis Position Control
Ladder program for normal operation and for restarting the system is needed for absolute infinite length axis
position control when the simple absolute infinite length position control function is not used.
(a) Normal Operation
1. Check the status of the Zero Point Return (Setting) Completed bit.
Check to see if the Zero Point Return (Setting) Completed bit (monitoring parameter IW
0C, bit 5) is
ON. If it is, go to step 2. If it is not, it means that the pulse position at power OFF, encoder position at
power OFF and all position data was not settled. In that case, restart the system and set up the position
data again or execute the ZSET (zero point setting) motion command to settle the position data all over
from the start.
2. Save the modularized position at power OFF and absolute position at power OFF.
Use the ladder program to save the following monitoring parameters with high-speed scan timing at an M
register backed up by battery.
• Monitoring parameter: Absolute Position at Power OFF (All four words at IL
5E to IL
60)
• Monitoring parameter: Modularized Position at Power OFF (All four words at IL
62 to IL
64)
The M register that is used to save the above monitoring parameters is structured as shown below.
Note: Two buffers are needed to save the absolute position and the modularized position at power
OFF because the program may be exited without settling position data at all four words if
power is turned OFF during the high-speed scan.
MW
Bit 0
Toggle Buffer Enabled Flag (OFF: Disabled, ON: Enabled)
Bit 1
Toggle Buffer Selection Flag (OFF: Buffer 0, ON: Buffer 1)
Bit 2
Position Data Re-setup Request Flag (OFF: Complete, ON: Request)
MW
+1
Not used
ML
+2
ML
+4
Buffer 0
Monitoring parameter:
Absolute Position at
Power OFF
Lower-place two words
(IL
5E
)
Upper-place two words
(IL
60
)
ML
+6
ML
+8
Monitoring parameter:
Modularized Position at
Power OFF
Lower-place two words
(IL
62
)
Upper-place two words
(IL
64
)
ML
+10
ML
+12
Buffer 1
Monitoring parameter:
Absolute Position at
Power OFF
Lower-place two words
(IL
5E
)
Upper-place two words
(IL
60
)
ML
+14
ML
+16
Monitoring parameter:
Modularized Position at
Power OFF
Lower-place two words
(IL
62
)
Upper-place two words
(IL
64
)
