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Max Quadrature Encoder Input Rate for Clipper ?


Unit101
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[quote='Unit101' pid='991' dateline='1294178563'] What is max quadrature encoder input rate for the Clipper ? 10KHz ? 50KHz ? Does this rate vary with other PMAC products ? Thanks, mike [/quote] The SLCK frequency must be at least four times higher than the maximum encoder cycle (line) frequency input, regardless of the quadrature decoding method used (with the most common times-4 decode, the SCLK frequency must be at least as high as the count rate). In actual use, due to imperfections in the input signals, a 20 – 25% safety margin should be used. If you set the encoder decode clock (SLCK) to 39MHz you can achieve bout 31 MHz quad rate. this is true for all Turbo PMACs.vkeep in mind this will reduce the nois filterring. See the PMAC User manual for details (Turbo version see page 52 printed electronic 68).
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Thanks Steve 1. for quick response and 2. memorizing all the manuals... you were exactly right, it is clear in the user manual I just did not find it. Here is some of the text from Turbo User Manual pdf pg68: -I put this here for others that may have the same question... The SLCK frequency must be at least four times higher than the maximum encoder cycle (line) frequency input, regardless of the quadrature decoding method used (with the most common times-4 decode, the SCLK frequency must be at least as high as the count rate). In actual use, due to imperfections in the input signals, a 20 – 25% safety margin should be used. The default SCLK frequency of 9.83 MHz is acceptable for virtually all applications. It can accept encoder signal cycle frequencies of up to about 2 MHz (8 MHz count rates) – with safety margin – and still provide decent digital filtering. This frequency may be changed by factors of two, up to 19.66 or 39.32 MHz on most designs, or down to as low as 1.25 MHz or 306 kHz on most designs. On some designs, an external SCLK signal can be provided. If very high encoder count rates are required, the SCLK frequency may have to be raised; if better filtering is required to prevent count errors, the SCLK frequency may have to be lowered.
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