— 6-27 —
6.3.3.2. Resolution of Pulse Train
The parameter CR (Circular resolution) can set the umber of pulses to make the Motor one
revolution. The Driver Unit controls the leftover pulses caused by dividing. (The origin of the
dividing calculation is the Home position of the position scale.)
◊ For an example, set the CR to 360 000 pulses for one revolution.
:
NSK ON
NSK ON
:
CR360000
:_
3
<
R C 6
&
0
?
0
?
ENT
0
?
0
?
K N S /
SP
N
ENT
O
The pulse train input frequency is up to 1 Mpps. This means that the maximum frequency of the
quadrupled øA/øB format is 4 M [count/sec]. When the parameter CR is set to 1 000 000
[count/revolution] in this case, the maximum rotational velocity is 4 s
-1
as shown bellow.
◊ 4 000 000 [count/sec] /1 000 000 [count/revolution] = 4 s
-1
Motor motion for the first pulse of the pulse train
When the parameter CR is set, the System sets grids on the position scale, which number is the
same as the division of one revolution with the value of parameter CR, starting from the origin of
the position scale. The positioning operation depends on the position of these grids.
However, the position of the Motor right after turning on the servo deviates from the position of
the grid in most cases. For this reason, the first pulse of a pulse train command compensates the
difference between the current Motor position and the grid.
Figure 6-17 below shows how the first pulse of a pulse train command compensates the Motor
position when the CR is set to CR327 680. In this case, the Motor motion distance for one pulse
of the pulse train input is equivalent to eight pulses of the Motor internal resolution.
(2 621 440/327 680 = 8 [pulse])
The Motor motion for the first pulse of the pulse train input in this case is:
◊ In the plus direction: Less or equal to 8 pulses of the Motor resolution
◊ In the minus direction: Greater or equal to 8 pulses and less or equal to 16 pulses of the
Motor resolution
Fig 6-17: Motor motion for the first pulse of a pulse train input
0
1
2
3
4
5
: Current
: Scale origin
1st pulse in plus
2nd pulse in plus
1st pulse in minus
Equivalent 8 pulses of Motor
327676
327677
327679
327678
+ direction– direction
Grid
2nd pulse in minus
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