Yaskawa FSP Amplifier - Manual (Page 159)

FSP Amplifier User’s Manual Chapter 5: Parameter Settings and Functions
5-92
Example:
A rotary motion system uses a motor with a 17-bit encoder. The user wants
to program the system in units of 0.1 degree:
17-bit encoder produces 131072 [counts] per revolution.
360 [degree] = 3600 [0.1 degree]
[ ] [ ]
ator deno ratio units Position
numerator ratio units Position
counts ree
min 3600
131072
deg 1 . 0 1 = =
First option: Second option:
Both options are equivalent.
5.9.1.3. Speed Units
Use the following parameters to convert speed units from [encoder
counts/msec] to [user speed units]:
Parameter Setting
Default
Setting
Signal
Pn2B4 Range: 1 to 65535 1 Speed units ratio numerator
Pn2B5 Range: 0 to 16383 0
Speed units ratio numerator
(high bits)
Pn2B6 Range: 1 to 65535 1 Speed units ratio denominator
Pn2B7 Range: 0 to 16383 0
Speed units ratio denominator
(high bits)
Speed user units are calculated according to the formula:
1[User speed unit] =
[ ]
[ ]
[ ]
r denominato ratio units Speed
numerator ratio units Speed
ms T
=
⎥
⎦
⎤
⎢
⎣
⎡ counts U
U = number of encoder counts in one speed unit.
T = time of speed units in ms.
The maximum value of numerator (Pn2B4) or denominator (Pn2B6) is
65535. In cases where greater values are required, it is possible to use
parameters Pn2B5 and Pn2B7 for storing the high bits of numerator and
denominator, respectively, according to the following formula:
It is possible to reduce the
fraction so that both the
numerator and denominator are
smaller than 65536:
131072 / 3600 = 32768 / 900
Æ Reduction
Pn2B0 = 32768
Pn2B1 = 0
Pn2B2 = 900
Pn2B3 = 0 Without reduction of the fraction:
High Bits = HB = Integer part of
N/65536 = Integer part of 131072
/ 65536 = 2
Low Bits = N – HB*65536 =
131072 – 2 * 65536 = 0
Pn2B0 = 0
Pn2B1 = 2
Pn2B2 = 3600
Pn2B3 = 0