CPR /LPI | 1" Disk Non-index | 1" Disk Index | 2" Disk Non-index | 2" Disk Index | Linear Strip Non-index | Linear Strip Index |
32 |
EM1-1-32-N |
|
|
|
|
|
50 |
EM1-1-50-N |
EM1-1-50-I |
|
|
|
|
64 |
|
|
EM1-1-32-N |
|
|
|
96 |
EM1-1-100-N |
EM1-1-100-I |
|
|
|
|
100 |
EM1-1-100-N |
EM1-1-100-I |
EM1-1-50-N |
EM1-1-50-I |
|
|
120 |
|
|
|
|
EM1-0-120-N |
EM1-0-120-I |
125 |
|
|
|
|
EM1-0-127-N |
EM1-0-127-I |
127 |
|
|
|
|
EM1-0-127-N |
EM1-0-127-I |
192 |
EM1-1-200-N |
EM1-1-200-I |
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|
|
|
200 |
EM1-1-200-N |
EM1-1-200-I |
EM1-1-100-N |
EM1-1-100-I |
EM1-0-200-N |
EM1-0-200-I |
250 |
EM1-1-250-N |
EM1-1-250-I |
|
|
EM1-0-250-N |
EM1-0-250-I |
256 |
EM1-1-250-N |
EM1-1-250-I |
|
|
|
|
300 |
|
|
|
|
EM1-0-300-N |
EM1-0-300-I |
360 |
EM1-1-360-N |
EM1-1-360-I |
|
|
|
|
400 |
EM1-1-400-N |
EM1-1-400-I |
EM1-1-200-N |
EM1-1-200-I |
|
|
500 |
EM1-1-500-N |
EM1-1-500-I |
EM1-2-500-N |
EM1-2-500-I |
EM1-0-500-N |
EM1-0-500-I |
512 |
EM1-1-512-N |
EM1-1-512-I |
EM1-2-500-N |
EM1-2-500-I |
|
|
720 |
EM1-1-720-N |
EM1-1-720-I |
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|
|
|
900 |
EM1-1-900-N |
EM1-1-900-I |
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|
|
|
1000 |
EM1-1-1000-N |
EM1-1-1000-I |
EM1-2-1000-N |
EM1-2-1000-I |
|
|
1024 |
EM1-1-1024-N |
EM1-1-1024-I |
EM1-2-1024-N |
EM1-2-1024-I |
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1250 |
EM1-1-1250-N |
EM1-1-1250-I |
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|
|
|
1800 |
|
|
EM1-2-1800-N |
EM1-2-1800-I |
|
|
2000 |
|
|
EM1-2-2000-N |
EM1-2-2000-I |
|
|
2048 |
|
|
EM1-2-2048-N |
EM1-2-2048-I |
|
|
2500 |
|
|
EM1-2-2500-N |
EM1-2-2500-I |
|
|
For more information, see the EM1/HEDS Compatibility Guide.
Other resolutions may be available upon request.
Encoding Characteristics:
- Specifications apply over entire operating temperature range.
- Values are for the worst error over full rotation.
- Refer to timing diagram below.
Parameter | Symbol | Min. | Typ. | Max. | Units |
Symmetry |
X, Y |
150 |
180 |
210 |
°e |
Quadrature |
Z |
60 |
90 |
120 |
°e |
Index Pulse Width |
Po |
60 |
90 |
120 |
°e |
Ch. I Rise After Ch. B or Ch. A Fall |
t1 |
50 |
100 |
200 |
ns |
Ch. I Fall After Ch. B or Ch. A Rise |
t2 |
-10 |
15 |
25 |
ns |
Timing Diagram:

CPR: The number of Cycles (C) of the A or B outputs Per Revolution.
Cycle Error: An indication of cycle uniformity. The difference between an observed shaft angle which gives rise to one electrical cycle, and the nominal angular increment of 1/CPR of a revolution.
Index (I): The index output goes high once per revolution, coincident with the low states of channels A and B, nominally 1/4 of one cycle (90 °e).
LPI: Lines Per Inch. The number of Cycles (C) of the A or B output per inch of linear strip movement.
One Shaft Rotation: 360 mechanical degrees.
One Electrical Degree (°e): 1/360th of one cycle.
One Cycle (C): 360 electrical degrees (°e). Each cycle can be decoded into 1 or 4 states, referred to as X1 or X4 resolution multiplication.
PPR: The number of resolvable Positions Per Revolution of the encoder disk with x4 quadrature decoding.
Quadrature (Z): The phase lag or lead between channels A and B in electrical degrees, nominally 90 °e.
Symmetry: A measure of the relationship between (X) and (Y) in electrical degrees, nominally 180°e.
US Digital is the designer and manufacturer of the EM1 transmissive optical encoder module. The design of the EM1 provides electrical and mechanical compatibility with HEDS-9000, HEDS-9100, HEDS-9200, HEDS-9040, and HEDS-9140 series modules.
The process of switching from the HEDS to the EM1 module should not require any mechanical or electrical changes. Simply use the EM1 and matching codewheel in place of the HEDS module and codewheel. The EM1 has a built-in index channel available on most resolutions, for both rotary disks and linear strips. The EM1 uses a US Digital designed codewheel with 2 tracks rather than 3 tracks for index versions. The EM1 offers improved output drive capability and will source and sink 8mA at TTL levels.
Physically, the EM1 has no external wire loops which can interfere when mounting. The connector pins are 0.051" shorter than HEDS modules, while still providing .30" insertion depth. US Digital's EM1 offers custom resolutions.