
SM-Universal Encoder Plus User Guide
47
Issue Number: 6
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Therefore to set-up a simulated encoder output of 1024 lines, the scaling has to be set
to a ratio of 1/16, parameter settings being: Pr
x.24
= Pr
3.29
, Pr
x.25
= 0.1, Pr
x.26
=
1.6 and Pr
x.28
= 0 (Ab).
Or the following parameter settings can be used:
Source - 65536 rollover parameter e.g Pr
3.29
, Pr
x.05
.
Encoder output - the encoder output resolution can be higher than the encoder
connected to the source, however quantisation effects need to be taken into
consideration, e.g 1 count on source may equal 10 on simulated output.
6.3.1
Simulated encoder source resolution
16-bit
The encoder output resolution at default will be 16-bit (source parameters range -32768
to 32767 or 0 to 65535) however this can be increased to 24-bit as detailed below.
24-bit
When using a high precision encoder as feedback i.e. SinCos, SSI or EndAt and the
source parameter, Pr
x.24
has been selected as Pr
x.05
position, the encoder output
resolution can only then be increased from 16-bit to a 24 bit position value by setting
Pr
x.27
encoder simulation resolution.
6.3.2
Software simulation: high resolution encoder
This situation occurs when the source parameter is Pr
x.05
(Position) of the same
module, the source device is a high precision encoder i.e. Comms only, and the
simulated encoder output is Ab or Fd and Pr
x.27
encoder simulation resolution is
selected.
The position Pr
x.05
and fine position Pr
x.06
are read every 250
µ
s with the output
being generated during the next period. This gives a simulated encoder output of the
main encoder with higher resolution (24 bit). The output position is defined as follows.
Output position = Counted input position x (Pr
x.25
/ Pr
x.26
)
Example:
in order to simulate one to one with a 13 bit (8192 count) comms only encoder
resolution. (The current position is taken in 16777216
ths
of a revolution (24 bit)). The
ratio down to 8192 pulses requires 1/2048, or 0.0001/0.2048. So Pr
x.25
= 0.0001 and
Pr
x.26
= 0.2048.
6.3.3
Software simulation: any other condition
If the source parameter is not as described above the parameter will be read every
250
µ
s and the output generated during the next period under software control within the
Solutions Module. The output position is defined as follows.
Output position = Parameter value x (Pr
x.25
/ Pr
x.26
)
Source
Encoder output
Pr x.25
Pr x.26
65536
4096
4096
1.6384
2048
2048
1024
1024
512
512
256
256
The simulated encoder output simulator has no information regarding the lines per
revolution of the source for the simulated encoder output. Instead, it treats this position
as a 16 bit or 24 bit number with roll-over / roll-under.
NOTE
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