Exposed Linear Encoders - DR. JOHANNES HEIDENHAIN GmbH - #51

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51 Position Detection Besides the incremental graduation, the LIF 4x1 features a homing track and limit switches for limit position detection. The signals are transmitted in TTL levels over the separate lines H and L and are therefore directly available. Yet the cable has only a very thin diameter of 4.5 mm in order to keep the forces on movable machine elements to a minimum. LIF 4x1 Output signals One TTL pulse for homing track H and limit switch L Signal amplitude TTL UH ‡ 3.8 V at –IH = 8 mA UL † 0.45 V at IL = 8 mA Permissible load R ‡ 680 - IILI † 8 mA Permissible cable length Max. 10 m r = Reference mark position s = Beginning of measuring length (ML) LI = Limit mark, adjustable h = Switch for homing track Ho = Trigger point for homing Limit switches Homing track LIF 400 Recommended input circuitry of the subsequent electronics Dimensioning IC3 e.g. 74AC14 R3 = 4.7 k-