Yaskawa MP920 Motion Module - Manual (Page 330)

7 PO-01 Module Specification and Handling
7.2.4 Out-of-step Detection
7-28
The example application program shown on the previous page is briefly explained below.
Initial Settings
The following initial settings are set when out-of-step detection is OFF (MB000000 is OFF).
Create a separate application program for out-of-step detection ON/OFF timing.
• Calculated feedback position (DL00000) = 0
• Remainder from the calculated feedback position calculation (DL00002) = 0
• DL00004 = Encoder pulse multiplier (n)
× number of encoder pulses per Servomotor
rotation (N)
Note: The encoder pulse multiplier (n) = 4 and the number of encoder
pulses per Servomotor rotation (N) = 2000 in this particular example,
but use settings appropriate for your machine.
• Reference position (DL00010) = 0
Feedback Position Calculation
The feedback position (P
i
) is calculated from the following: The input data for the Counter
Module (number of pulses per scan: IL1002), the number of reference pulses per Servomo-
tor rotation (M), the encoder pulse multiplier (n), and the number of reference pulses per
Servomotor rotation (M).
Note: The number of reference pulses per Servomotor rotation (M) = 2000
in this particular example, but use settings appropriate for your
machine.
Execute Out-of-step Detection Calculation
If the absolute difference between the reference position (M
i
) and the calculated feedback
position (P
i
) exceeds the error width ( ε), then the situation is considered out of step and
OB00000 turns ON.
Note: The error width ( ε) = 200 in this particular example, but use settings
appropriate for your machine.
„ Guidelines for Setting Error Width
Set the error width to four times the number of output pulses per scan when the Servomotor is running
at the rated motor speed (rpm).
• NR: Rated motor speed (rpm)
• Ts: High-speed scan setting (ms)
We get the following result if NR = 300 (rpm), the number of reference pulses per Servomotor rotation
= 2000 pulses, and Ts = 5.
• ε = { (300 × 2000 × 5) ÷ (60 × 1000) } × 4 = 200
INFO