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8   ZERO POINT RETURN CONTROL 

 

8.2.2 Machine zero point return method 

The method by which the machine zero point is established (method for judging the 
zero point position and machine zero point return completion) is designated in the 
machine zero point return according to the configuration and application of the 
positioning method.  
The following table shows the six methods that can be used for this zero point return 
method.  
(The zero point return method is one of the items set in the zero point return 
parameters. It is set in "

Pr.45  Zero point return method" of the basic parameters for 

zero point returns.) 

 

 

Pr.45  Zero point return 

method 

Operation details 

Near-point dog method 

When near-point dog turns from OFF   ON, deceleration is started.  
(Speed decreases to " Pr.49  Creep speed".) 

After near-point dog has turned from ON   OFF, a stop is made at the first zero 
point signal*, and the machine zero point return is regarded as completed at 
completion of deviation counter clear output. 

Stopper stop method 1) 

The stopper position is defined as the zero point. 
After deceleration is started when near-point dog turns from OFF   ON, the 
machine is brought into contact with the stopper at " Pr.49  Creep speed" to a stop.

After " Pr.51  Zero point return dwell time" has then elapsed, the machine zero 

point return is regarded as completed at completion of deviation counter clear 
output. 

Stopper stop method 2) 

The stopper position is defined as the zero point. 
After deceleration is started when near-point dog turns from OFF   ON, the 
machine is brought into contact with the stopper at " Pr.49  Creep speed" to a stop.

After the zero point signal* is then detected, the machine zero point return is 
regarded as completed at completion of deviation counter clear output. 

Stopper stop method 3) 

The stopper position is defined as the zero point. 
The machine starts at " Pr.49  Creep speed" from the beginning, and is brought 

into contact with the stopper at " Pr.49  Creep speed" to a stop. 

After the zero point signal* is then detected, the machine zero point return is 
regarded as completed at completion of deviation counter clear output. 

Count method 1) 

When near-point dog turns from OFF   ON, the machine starts deceleration and 
moves at " Pr.49  Creep speed". 

After the machine has moved the distance set in " Pr.52  Setting for the 

movement amount after near-point dog ON" from the position where near-point 
dog turned from OFF   ON, it stops at the first zero point signal*, and the 
machine zero point return is regarded as completed at completion of deviation 
counter clear output. 

Count method 2) 

When near-point dog turns from OFF   ON, the machine starts deceleration and 
moves at " Pr.49  Creep speed". 

The machine stops after moving the distance set in " Pr.52  Setting for the 

movement amount after near-point dog ON" from the position where near-point 
dog turned from OFF   ON, and the machine zero point return is regarded as 
completed. 

 

*: The zero point input signals of the D75P2 in each zero point return method are described below. 

Near-point dog method and count method 1):  One-pulse signal output per each motor revolution 

(Z-phase signal output from drive unit, etc.) 

Stopper stop method 2), 3): 

Signal output upon detection of contact with stopper 
(Supplied from an external device) 

REMARK 

Creep speed 

The stopping accuracy is poor when the machine suddenly stops from high 
speeds. To improve the machine's stopping accuracy, its must change over to a 
low speed before stopping. This speed is set in the " Pr.49  Creep speed".