Industrial Indexing Systems MSC-250 User Manual

INDUSTRIAL INDEXING SYSTEMS, INC. IB-11B012
MOTION CONTROL SYSTEM, MSC-250 USER'S GUIDE
MARCH 2003 DESCRIPTION 1 - 7
Figure 1.4 - Typical Encoder Pulse Patterns
Encoders may have different line counts per one revolution of the encoder. This line count
is an important factor in determining the performance of the system. High line count
encoders offer high resolution and accuracy, but affect speed and acceleration rates. Low
line count encoders provide higher speed and acceleration, but resolution is reduced. The
standard line count assumed by the MSC-250 controller and the Macroprogram software is
1024 pulses per revolution.
NOTE
To use encoders with line counts other than 1024, the values for
RPM and acceleration must be properly scaled to provide accurate
motor shaft movement (refer to the Macroprogram Development
System Instruction Book).
The marker provided by channel M is also a square-wave signal. However, different
encoders use markers of varying duration. The marker bit may go high (positive
amperage) for a single pulse width, for 90° of encoder shaft revolution, or for 180° of
encoder shaft revolution. When this pulse goes high in a clockwise rotation (or low in a
counterclockwise rotation), the controller uses the state change to mark the "0.00" absolute
reference point.
The encoder is not an absolute position sensing device. When first powered up, the
encoder shaft position in its rotation cannot be determined until the marker bit is recorded.
Rather, the position at power up is referred to as "local mode home" or "0.0" as opposed to
absolute 0.00. The controller can determine actual movement from this local home
position by counting pulses.

Industrial Indexing Systems MSC-250 Specifications

General

Brand	Industrial Indexing Systems
Model	MSC-250
Category	Controller
Language	English