HD25A Product Description The HD25A is a NEMA 25 sized absolute encoder designed for industrial applications. The HD25A optical encoder is a 12-bit absolute rotary position sensor, which reports a shaft angle within a single 360-degree rotation of a shaft. Unlike incremental, sometimes called relative style encoders, the HD25A provides true (absolute) shaft position, eliminating the need for a home or zero cycle after a supply voltage power cycle. The HD25A communicates over a RS 485-style serial bus utilizing US Digital's SEI (Serial Encoder Interface) which allows for simple, quick, and convenient networking of multiple SEI devices on a single network. PLCs, motion controllers, and computers can also reside on the SEI bus as well by use of US Digital's SEI to USB interface device. For complete information about the SEI bus please refer to the SEI Communications Protocol webpage.
The HD25A also provides an analog output. The analog output provides a maximum voltage range of 0 to 4.095 volts with 12-bit resolution. The output voltage can be scaled by simple SEI commands to provide user-defined voltage ranges. From the factory, the analog output voltage is set to 0 to 3.599 VDC range.
Product Specifications
ENVIRONMENTAL
Parameter
Value
Units
Operating Temperature
-25C to 70C
C
Vibration (5 to 2kHz)
20
G
Shock, 11 mSec
60
G
Electrostatic Discharge, IEC 61000-4-2
± 4
kV
MECHANICAL
Parameter
Value
Size
NEMA 25
Housing and Cover Material
Anodized aluminum
Weight
16.91 oz.
Shaft Material
Stainless steel
Shaft Diameter
0.3748 in. (+0.0000 in. -0.0004 in.)
Shaft Optional Flat Size
0.80 in. long x 0.03 in. deep
Max. Acceleration
100000 rev / sec²
Max. Shaft Speed
Max. Shaft Torque
Max. Shaft Load
Max. Shaft Runout
0.0003 in. T.I.R.
Bearing Life @ 4 Pound Load
2.3 x 10^9 revolutions
Moment of Inertia
2.8 x 10 ^-4 oz-in-sec²
Technical Bulletin TB1001 - Shaft and Bore Tolerances
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ELECTRICAL
Specifications apply over entire operating temperature range.
Typical values are specified at Vcc = 12V and 25C.
Parameter
Min.
Typ.
Max.
Units
Supply Voltage
7.5
12
16
V
Supply Current
Analog Output Impedance
51
Ohms
Zero Scale Analog Voltage
0
2
12
mV
Full Scale Analog Voltage
4.066
4.095
4.124
V
Output Noise (Analog version)
10
mV rms
Differential Nonlinearity
-1.0
1.0
LSB
Absolute Accuracy (SEI interface version)
0.18
0.25
Degrees
Angle tracking speed
Position Update Rate (1)
7
msec.
(1) The internal microcontroller takes a snapshot of the disk every 7 msec. and stores the position in memory. It responds immediately to a "report position request" by sending the most recently computed position.
DEFAULT SETTINGS
Parameter
Default value
Volatile?
SEI address
0
Non-volatile
Resolution
3600
Non-volatile
Origin offset
0
Non-volatile
Baud rate
9600
Volatile
Mode
0
(1)
(1) Mode is always restored from non-volatile EEPROM on power-up; however, there are separate SEI commands for setting the RAM copy only, or both the RAM copy and the non-volatile EEPROM copy. For an explanation of the Mode bits see SEI Absolute Encoder Communications Protocol .
ANALOG OUTPUT
In addition to the SEI interface, the HD25A also provides a 0 to 4.095 V analog output (1 mV per count). The absolute position value which the internal microcontroller sends to the 12-bit DAC is the same as the digital value that it sends to the host over SEI. Since the resolution (which represents the number of codes per revolution) is field programmable, the range of the DAC will also follow that setup. The default resolution is 3600 codes per revolution which yields 1 count per tenth of a degree. This makes the DAC output equal to 1 mV per tenth of a degree or 0 to 3.599 Volts. When the DAC needs to have the full range to 4.095 Volts, the single turn resolution should be set to 4096. This is easily done with the available software which runs on a PC.
PIN-OUTS
PIN
DESCRIPTION
A
Data H
B
Busy+
C
Analog+
D
Power
E
NC
F
Ground
G
Case Ground
H
Data L
I
Busy-
J
Analog-
PRODUCT CHANGE NOTIFICATIONS
Title
Date
Description
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A2/HD25A Product Lines Detector Upgrade
8/18/2014
As part of our ongoing continuous improvement efforts, US Digital is updating our A2 and HD25A product lines design by utilizing surface mount devices for the detector and LED. Previously these were through hole devices. This change is transparent with the exception of minor cosmetic differences for the A2 kit style encoder, and Spacer Tool used in kit assembly process.
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Additional Information
Product Notes
Cables and connectors are not included and must be ordered separately.
US Digital® warrants its products against defects in materials and workmanship for two years. See complete warranty for details.
Guides and Additional Documentation
Software
3D Model Downloads
Please
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to download a 3D model. (Note: The formats below will become links if there are 3D models available.)
SolidWorks Format
IGES Format
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STEP Format
Datasheet
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