Speed Units - Omron XTRADRIVE User Manual

XtraDrive User Manual
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]
[
1 0 1 . deg
First option:
It is possible to reduce the
fraction so that both the
numerator and denominator are
smaller than 65536:
131072 / 3600 = 32768 / 900
Reduction
Pn2B0 = 32768
Pn2B1 = 0
Pn2B2 = 900
Pn2B3 = 0
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
Pn2B4
Pn2B5
Pn2B6
Pn2B7
Speed user units are calculated according to the formula:
1[User speed unit] =
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:
HighBit
LowBits
131072
] [ ]
=
ree counts
3600
Setting
Setting range 1-65535
Setting range 0-16383
Setting range 1-65535
Setting range 0-16383
[

U counts

[ ]
T ms

= =
HB Integerpar tof
= − •
, where N- required value.
65536
N HB
5-92
Chapter 5: Parameter Settings and Functions
Position units ratio
=
Position units ratio deno
Second option:
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
Default
Setting
1 Speed units ratio numerator
Speed units ratio numerator
0
(high bits*)
1 Speed units ratio denominator
Speed units ratio denominator
0
(high bits*)
]
[

=
Speed units ratio numerator

Speed units ratio denominato

N
65535
numerator
min
ator
Signal
]
r