Normal operation – Yaskawa MP920 User's Manual Design User Manual

Page 466

10.3 Using an Absolute Encoder

10-21

Ladder Logic Program for Infinite Length Mode Axis Position Control

Special ladder logic programs for normal operation and for restarting the system are needed
for absolute Infinite Length Mode Axis position control when an absolute encoder is used as
an Infinite Length Mode Axis.

Normal Operation

1. Check the Zero Point Setting Complete status.

Check to see if monitor parameter Zero Point Setting Completed (IW

15 bit 3) 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 checked. In that case, restart the system and set up the posi-
tion data again or execute the ZSET motion command (zero point setting) to check the
position data all over from the start.

2. Save the pulse position at power OFF and encoder position at power OFF.

Use the customer’s ladder logic program to save the following monitor parameters with

high–speed scan timing at an M register backed up by battery.

The M register that is used to save the above monitor parameters is structured as shown

below.

Note: Two buffers are needed to save the encoder position and the pulse

position at power OFF because the program may be exited without
checking position data at all four words if power is turned OFF dur-
ing the high-speed scan.

Monitor parameter: Encoder Position at Power OFF (All four words at IL38 to IL3A)
Monitor parameter: Pulse Position at Power OFF (All four words at IL3C to IL3E)

MWxxxxx

Bit 0

Toggle Buffer Enabled Flag (0: Disabled/1: Enabled)

Bit 1

Toggle Buffer Selection Flag (0: Buffer 0/1: Buffer 1)

Bit 2

Position Data Re-setup Request Flag (0: Complete/1: Request)

MWxxxxx +1

Not used

MLxxxxx +2
MLxxxxx +4

Buffer 0

Monitor parameter:
Encoder Position at Power OFF

Lower-place two words (IL38)

Upper-place two words
(IL3A)

MLxxxxx +6
MLxxxxx +8

Monitor parameter:
Pulse Position at Power OFF

Lower-place two words
(IL3C)

Upper-place two words (IL3E)

MLxxxxx +10
MLxxxxx +12

Buffer 1