Alarm Detection - YASKAWA SGMJV User Manual

8 Fully-closed Loop Control

8.3.6 Alarm Detection

 Setting Example
A setting example is given below.
If the servomotor moves 0.2 μm for every pulse of position reference, the external encoder sine wave pitch is
20 μm, and the number of divisions is 256, the electronic gear ratio will be as follow.
Electronic gear ratio
Therefore, set 512 for Pn20E (numerator B) and 200 for Pn210 (denominator A).
8.3.6
Alarm Detection
The setting of alarm detection (Pn51B/Pn52A) is shown below.
(1) Excessive Error Level between Servomotor and Load Positions (Pn51B)
This setting detects the difference between the feedback position of the motor encoder and the feedback load
position of the external encoder in fully-closed loop control. If the detected difference is above the set level,
the motor-load position error overflow alarm (A.d10) will be output.
Pn51B
Note: When Pn51B is set to 0, the motor-load position error overflow alarm (A.d10) is not detected.
(2) Multiplier per One Fully-closed Rotation (Pn52A)
The coefficient of the error between the external encoder and the motor per motor rotation can be set. This
function can be used to prevent the motor from running out of control due to damage to the external encoder or
to detect slippage of the belt.
 Setting Example
Increase the value if the belt slips or is twisted excessively.
If the set value is 0, the external encoder value will be read as it is.
If the factory setting of 20 is used, the second rotation will start with the error for the first motor rotation mul-
tiplied by 0.8. (Refer to the following figure.)
Error between motor and external encoder
8-22
B Pn20E
= = =
A Pn210
Excessive Error Level between Servomotor and
Load Positions
Setting Range Setting Unit
0 to 1073741824 1 reference unit
Big
Small
Less than
one rotation
0.2 × 256
512
= =
20
200
Position
Factory Setting
1000
Number of motor rotations
1st 2nd
rotation rotation
Classifica-
tion
When Enabled
Immediately
Setup
Pn52A=0
Pn52A=20
Pn52A=100
3rd
rotation