IC-MN_16 Datasheet, PDF (49/62 Pages) IC-Haus GmbH – 25-BIT NONIUS ENCODER WITH 3-CH. SAMPLING 13-BIT Sin/D INTERPOLATION

iC-MN 25-BIT NONIUS ENCODER
WITH 3-CH. SAMPLING 13-BIT Sin/D INTERPOLATION
Rev F2, Page 49/62
MTMA
MTSLI
MSB
LSB
DL_MT + SBL_MT
tout
respectively trailing operation. The green arrows are
indicating the permissible relative position tolerances.
max
max
Figure 23: Line signals of the serial MT interface
MODE_MT = 0x10 (SSI)
MT Interface with 2-bit mode
In this mode pin MTMA functions as an additional in-
put, besides pin MTSLI. The inputs now expect digital
signals phase shifted by 90°, whereas MTMA reads
the single bit period information, and MTSLI the shifted
synchronization bit. The following figure explains the
principle and the table below gives the necessary set-
tings.
sector 0
sector 1
MTSLI
(LSB)
MTMA
(MSB)
binary
signal
3
0
1
23
calculated nonius position
max
max
master
sector 0
sector 1
0
360°
°/rev
.
2 bit sector code (gray coded)
0
360°
°/rev
.
segment
nonius
MTSLI
MTMA
iC-MN
resulting dataword
2*max
0
360°
°/rev
.
Figure 24: Principle of 2-bit mode
Parameter
MODE_MT = 11
DL_MT = 0x0E
SBL_MT = 00
LNT_MT = 0 or 1
GRAY_MT = 1
M2S = 11
Description
MT interface op. mode: 2-bit mode
MT data length: 1 bit
Synchronization bit length: 1 bit
Depending on MTMA signal: leading or
trailing
MT data format: Gray coded
Enable for MT plus ST data output
Table 89: Required settings for 2-bit mode
The required position of the multiturn and synchro-
nization bit depends on parameter LNT_MT. Figure
25 shows the required signal positions with leading
MTSLI
(LSB)
MTMA
(MSB)
binary
signal
01
2
30
0° 45° 90° 135° 180° 225° 270° 315° 0°
°/rev
Figure 25: Position of switch points in reference to
the parameter LNT_MT
A typical application example where the 2-bit mode can
be used for, is a magnetic angle encoder scanning the
pole wheel by MR sensors. A nonius coded wheel of 16,
15 and 12 pole pairs yields 32, 30 and 24 sine periods
per turn on iC-MN’s analog inputs. The nonius calcu-
lation would not produce absolute angle position data
over a single revolution since the maximum singleturn
value is achieved twice. The distinction as to which half
of the revolution the axis is in can only be made using
section sensors, two Hall sensors for example, whose
digital outputs are connected up directly to MTMA and
MTSLI. Furthermore, the 2-bit mode can be used also
with systems based on a 2 track nonius calculation.