1. Encoder Type:
Centroid Acorn CNC controller Encoder input requires quadrature, differential encoders for Spindle encoder use which operate on 5VDC. This is the most common type of encoder. Encoders labeled "TTL type" (single ended, non differential) are unsuitable, and fortunately are rare and converter boxes are not recommended.
2. Encoder Signals:
a) The following signals must be present and wired: A, /A, B, /B, Z, /Z, +5VDC and ground.
Note: The Z channel is sometimes labeled as I, C or "marker". The "/" symbol may also be
expressed as "-", "NOT" or "!" or a line over the letter, it means the signal is the complement
(opposite) of the channel specified.
b) Signal levels:
The "low" signal level must be less than 0.5 VDC and the "high" signal level must be at least 3.5 VDC. ACORN supplies around 50mA that is typical of most encoders.
3. Spindle Encoder Resolution:
Typical Machine tool applications (milling machines, lathes and routers) require at least 500 line (2000 counts per rev) encoders, We recommend any where from 500 to 2000 line (= 2000 to 8000 counts per rev) encoders for spindle applications. To achieve reasonable accuracy for good threading and rigid tapping.
4. Also consider the max. frequency for spindle encoders, this relates to the useable Maximum RPM that the encoder can operate at.
Most cheap encoders are limited to 3000rpm with 2000 lines, with 1000 lines to 6000rpm.
Rigid Tapping works great even at low line counts such as 400 or 500 line (1600 counts per rev, 2000 counts per rev)
Encoder wiring at the Acorn
DB9 Body = Cable Shield
Pin Function
1 No Connection
2 GND
3 Z\
4 A\
5 B\
6 Z
7 A
8 B
9 +5 VDC
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