IB-11B012 USER'S GUIDE
INDUSTRIAL INDEXING SYSTEMS, INC. MOTION CONTROL SYSTEM, MSC-250
When the absolute position of the system must be known, the system must be initialized after it is powered up. For encoders with marker bits less than 180° of encoder shaft rotation, use the find_mark_cw and find_mark_ccw commands to initialize the system and determine the absolute system position. For encoders with marker bits of 180° of encoder shaft rotation, use the find_tm_cw and find_tm_ccw commands. (Refer to the Macroprogram Development System Instruction Book for complete command instructions.)
NOTE The ability to find a marker or initialize the system is only valid when the controller is being used as an active (versus passive) position sensing device and does not affect the master angle data.
1.2.1.2
POS OUT Signal
The position of the encoder, as understood by the controller, is translated into a "POS OUT" voltage signal based on a digital compensation gain algorithm. This algorithm has four variable components of Proportional Gain, Integral Gain, Derivative Gain, and Feed Forward Gain values which respectively represent the Proportional, Integral, Derivative, and Feed Forward terms of the algorithm. With standard values of Proportional Gain = 16, Integral Gain = 0, Derivative Gain = 0, and Feed Forward Gain = 0, the POS OUT voltage signal is +5 VDC at the 90° encoder shaft position and +10 VDC at the 180° encoder shaft position for clockwise shaft rotation. The signal is -5 VDC at the 90° encoder shaft position and -10 VDC at the 180° encoder shaft position for counterclockwise shaft rotation. However, the Proportional Gain value can be set to produce a voltage signal of from 10 VDC per 1/32 revolution of the encoder shaft to 10 VDC per 8 turns of the encoder shaft. (Refer to the Macroprogram Development System Instruction Book for information on setting the digital compensation values.)
1.2.1.3
Pseudo Axis
The pseudo axis is an imaginary, perfect motor which can be controlled by the software of the MSC-250. The desired position of the pseudo-axis motor is determined by the Macroprogram and the resulting position signal perfectly reflects the desired position at any given time. This perfect-position information can then be used by the real axes as reference information for their own movements or it can be used to actuate programmable limit switches or other I/O functions. The pseudo axis information can be broadcast (transmitted) on either or both of the controller master angle buses.
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MARCH 2003
