8

Electrical Interface

To insure reliable encodingperformance, the HEDS-

5540/5640 and HEDM-5540 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 resistors should be located as close to the

encoder as possible (within 4 feet). Each of the three

Figure 1. Pull-up Resistors on HEDS-5X40 and HEDM-5540 Encoder Outputs.

encoder outputs can drive a single TTL load in this con-

figuration. The HEDS-5500, 5600, and HEDM-5500, 5600

two channel encoders do not normally require pull-up

resistors. However, 3.2 kΩ 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 fre-

quencies.

Mechanical Characteristics

Parameter

Symbol

Dimension

Units

Codewheel Fits These Standard

Shaft Diameters

2 3 4

5 6 8

+0.000

-0.015

mm

5/32 1/8

3/16 1/4

+0.0000

-0.0007

in

Moment of Inertia

J

Required Shaft Length[2]

14.0 (0.55)

± 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)

mm (in.)

3 screw mounting

M 1.6 or (0-80)

mm (in.)

external mounting ears

M 2.5 or (2-56)

mm (in.)

Encoder Base Plate Thickness

0.33 (0.130)

mm (in.)

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).