LYCOS RETRIEVER 
Encoder: Encoder Counts
built 646 days ago
The zero-index configuration defines the manner in which the encoder circuitry reads the zero-index pulse from the encoder, and is set to match the specific type of encoder in use. The zero-index is often used as a calibration reference. (The zero-index pulse is ... sometimes known as the Index Pulse, the Marker Pulse or the C-channel.) It may also be used, in conjunction with the Encoder Counts per Zero Index parameter, to help detect certain encoder faults. Zero-index pulses may be active low or active high, and an active pulse transition may occur in conjunction with the rising or falling edge of either the A or B channel. Most encoder manufacturers provide timing diagrams that describe the relationship of the zero index pulse to the A and B channels. The timing diagram indicates the most reliable point at which to set the zero-index configuration.
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The Number of Pulses Per Revolution (PPR) is always stated as actual lines (true lines or real holes) on the disk, inside the encoder. Pulses can be multiplied by x2 or x4. (Example: 12.500 Pulses x 4 = 50.000 Counts). Depends on PLC or controller.
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It is ... recommended that you derive as many quadrature counts from the AZ Encoder as possible, but not exceeding 65,256 quadrature counts in the full 360deg's. The ratio of revolutions MAST relative to Encoder can be any ratio needed to reach the above number. An example would be an US Digital H3-2048, the turns ratio can be 31.375 : 1, with the LS-7084 quadrature converter set to X 1.
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In MDrive applications that require continuous slew, such as pumps or fans, and encoder mode is enabled, a stall error will occur when the encoder counter overflows. An easy way to avoid this is to use trip on position (Tp) to reset the position counter occasionally. The sample program demonstrates the use of Tp and sets a Pause / Resume input and a Fault output.
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Excessive noise may cause encoder zero-index errors. If the noise is repeatable, use the Max accumulated encoder noise counts and Max encoder noise counts per rev parameters to establish a noise tolerance that will allow some index errors to occur before generating an index error. For non-repeatable noise, temporarily disable the encoder zero-index checking parameter. However, even if zero-index error-reporting is disabled, the correct zero-index configuration will still be required if the zero-index is used for calibration. (See Encoder (Zero Index) Configuration for details on configuring the encoder.)
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'*** This program uses a trip on position to '*** reset the position counter every 100000 '*** encoder counts. Ee=1 'enable encoder P=0 'init pos counter S1=6,0,0 'configure as pause/resume S4=18,0,0 'configure as fault output PG 1 LB su Tp 100000,fj 'on position trip call fj Te=2 'enable trip SL 3000 'continuous slew H E 'program end LB fj P=0 'reset postion counter PR "reset" 'just here to show it's been called Te=2 'reenable position trip RT 'return PG S
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Encoder Counts