7
Mechanical Characteristics
Parameter
Symbol
Dimension
Tolerance[1]
Units
Codewheel Fits These
Standard Shaft Diameters
2 3
5 6
4
8
+0.000
-0.015
mm
5/32 1/8
3/16 1/4
+0.0000
-0.0007
in
Moment of Inertia
J
0.6 (8.0 x 10-6)
14.0 (0.55)
g-cm2 (oz-in-s2)
Required Shaft Length[2]
± 0.5
(± 0.02)
mm
(in.)
Bolt Circle[3]
2 screw
mounting
19.05
(0.750)
± 0.13
(± 0.005)
mm
(in.)
3 screw
mounting
20.90
(0.823)
± 0.13
(± 0.005)
mm
(in.)
external
mounting ears
46.0
(1.811)
± 0.13
(± 0.005)
mm
(in.)
Mounting Screw Size[4]
2 screw
mounting
M 2.5 or (2-56)
M 1.6 or (0-80)
mm (in.)
mm (in.)
3 screw
mounting
external
mounting ears
M 2.5 or (2-56)
0.33 (0.130)
mm (in.)
mm (in.)
Encoder Base Plate
Thickness
Hub Set Screw
(2-56)
(in.)
Notes:
1. These are tolerances required of the user.
2. The HEDS-55X5 and 56X5, HEDM-5505, 5605 provide an 8.9 mm (0.35 inch) diameter hole through the housing for longer motor
shafts. See Ordering Information.
3. The HEDS-5540 and 5640 must be aligned using the aligning pins as specified in Figure 3, or using the alignment tool as shown in
“Encoder Mounting and Assembly”. See also “Mounting Considerations.”
4. The recommended mounting screw torque for 2 screw and external ear mounting is 1.0 kg-cm (0.88 in-lbs). The recommended
mounting screw torque for 3 screw mounting is 0.50 kg-cm (0.43 in-lbs).
Electrical Interface
To insure reliable encoding
pull-up resistors on output pins 3
and 5 (Channels A and B) are
recommended to improve rise
times, especially when operating
above 100 kHz frequencies.
close to the encoder as possible
(within 4 feet). Each of the three
encoder outputs can drive a single
TTL load in this configuration.
performance, the HEDS-5540 and
5640 three channel encoders
require 2.7 kΩ (± 10%) pull-up
resistors on output pins 2, 3, and
5 (Channels I, A, and B) as shown
in Figure 1. These pull-up
The HEDS-5500, 5600, and
HEDM-5500, 5600 two channel
encoders do not normally require
pull-up resistors. However, 3.2 kΩ
resistors should be located as
HP [ HEWLETT-PACKARD ]
