Normal operation – Yaskawa MP940 User Manual

Page 334

Absolute Position Detection

7.3.2 Infinite Length Mode Axis

7-20

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 (IWC015 bit 3) is ON.
If it is, go to step 2.

If it is OFF, 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
position 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 ILC038 to
ILC03A)
Monitor parameter: Pulse Position at Power OFF (All four words at ILC03C to
ILC03E)

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 (ILC038)

Upper-place two words (ILC03A)

MLxxxxx +6
MLxxxxx +8

Monitor parameter:
Pulse Position at Power OFF

Lower-place two words (ILC03C)

Upper-place two words (ILC03E)

MLxxxxx +10
MLxxxxx +12

Buffer 1