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| | | Description of the reference marks | | |
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| | | In order to determine the absolute angular position in the direction of measurement between the scanning head and the measuring flange, a reference track is integrated on to the scale, disposed parallel to the measuring track. This reference track consists of one or more reference marks (correspondingly marked on the measuring ring), which are detected by the sensors in the scanning head. The reference marks can be arranged in the following ways: | | |
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| | | Identifier: | | |
| | | 1. Single reference marks These can be placed at any angular desired location on the measuring ring. The standard arrangement is for a single reference pulse to be output for each revolution, assigned to a mounting hole in the measuring flange. 2. Distance-coded reference marks Coded distribution of these marks on the measuring ring allows the controller, if it is capable of this function, to determine the absolute position after passing two neighbouring marks. All the WMI systems are offered with coded reference marks having the following basic spacings (K): | | |
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| | | Reference mark | | |
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| | | Basic spacing J k=xx> | | |
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| | | Positive direction of counting | | |
| | | First basic mark | | |
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| | | | | | | | | | | | | | | WMI-0360-K1 | WMI-0512-K3 | WMI-0720-K1 | WMI-0900-K2 | WMI-1024-K3 | | | | Basic spacing K in number of periods | 40 | 64 | 40 | 60 | 64 | | | | Absolute position after max. | 40° | 45° | 20° | 24° | 22,5° | | | | | | | | | | | | | |
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| | | Signal subject to analog dividing (dividing factor D=1) K' -> Number of sinus periods after division at the output of the measuring system | | |
| | | Signal not divided (dividing factor D=1) K -> Number of sinus periods of 1000 jum arc length at the output of the measuring system K _ , _ K ^_ | | |
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| | | K' = K x D | | |
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| | | |f-2D | | f+3D | | |
| | | ■+2 | | -+3 | | ■2+2D | | |
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| | | K+1 | | K+1 | | K'+D | | K'+D | | |
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| | | Direction of counting | | Direction of counting | | |
| | | 360° | | 0° | | | 360° | | |
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| | | Description of the output signals | | |
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| | | 1 Vpp output signals Recommended configuration of the subsequent electronics: | | |
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| | | • A+, B+, RI+ (and their inverted signals): direct signal output with dividing factor D=1 • A+, B+, RI+ (and their inverted signals): divided signal output with dividing factor D=1 TTL - RS422 output signals Recommended configuration of the subsequent electronics: | | |
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| | | I | | |
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| | | f TX | | |
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| | | 9fi | | |
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