Rockwell Automation 845D Absolute Encoder, Size 25 User Manual
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Electrical Connections
Function
Pin
Gray Code
Natural Binary
BCD (8421)
A
G(0)
2
0
1
B
G(1)
2
1
2
C
G(2)
2
2
4
D
G(3)
2
3
8
E
G(4)
2
4
10
F
G(5)
2
5
20
G
G(6)
2
6
40
H
G(7)
2
7
80
J
G(8)
2
8
100
K
G(9)
2
9
200
L
MSB Complement
Not Used
400
M
Not Used
Not Used
800
N
Not Used
Not Used
Not Used
P
Not Used
Not Used
Not Used
R
Not Used
Direction Control
Direction Control
S
Reset
Reset
Reset
T
DC Return
DC Return
DC Return
U
Not Used
Latch Control
Latch Control
V
DC+ Input
DC+ Input
DC+ Input
Direction Pin
The Direction Pin can change function with code type. In
parallel type Gray Code encoders, its function is Most
significant Bit Complement or MSBC for short. In Natural
Binary and Binary Coded Decimal encoders, its function is
Direction Control.
Direction Control
Ê
Natural Binary and BCD
A logic “1” (+DC or open) on the direction control pin will
produce increasing counts with a counter- clockwise rotation
of the shaft. A logic “0” (DC common) on the direction control
pin will produce increasing counts with a clockwise rotation of
the shaft.
Gray Code (parallel only)
Counterclockwise rotation of the shaft will produce increasing
counts. For increasing counts with a clockwise rotation, use
the Most Significant Bit Complement Pin instead of the Most
Significant Bit Pin. See Electrical Connection table for pin
designation.
ATTENTION: For parallel gray code: connecting the
MSB or MSBC to +DC will result in permanent
damage to the encoder.
Reset Pin
The shaft must be stationary before using the reset function.
Connecting the Reset Pin to +DC will reset Natural Binary and
BCD position value to zero. Connecting the Reset Pin to +DC
will reset Gray Code position value to maximum (e.g., 255,
511, 1023, etc.) if MSBC is used, to zero if MSB is used. The
reset function requires a connection to +DC for 0.1 seconds or
longer.
ATTENTION: Activating the Reset Pin results in a
change of position reading. This can cause
unexpected motion which could result in damage to
the product, equipment, or personal injury.
Flexible Shaft Couplings
Angle
Parallel
OffĆSet
ATTENTION: Rigidly coupling the encoder shaft to
the machine shaft will cause a failure in either the
bearings of the encoder or the bearings of the
machine shaft.
Ê
Rotation is viewed from the end of the encoder shaft.