Table Of Contents

Safety Response Time Specifications

Version:
    Last Modified: September 6, 2017

    Use these specifications to calculate safety response times for your C Series Functional Safety system.

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    Note  

    These specifications list minimum guaranteed times unless otherwise noted.

    Total C Series Functional Safety module response time

    Single input and dual input

    122 µs

    Single input with test pulse and dual input with test pulse

    230 µs

    Input signal response time (1 to 0)

    Single or dual input

    57 µs

    Single or dual input with test pulses

    165 µs

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    Note  

    Input signal response time (1 to 0) assumes a 3 kΩ external pull-down, 50 m cable length with capacitance <180 pF/m, and the debounce filter and test pulse width set to the minimum values for the given configuration.

    Input signal response time (0 to 1)

    Single input

    20 µs

    Dual input

    122 µs

    Single input with test pulses

    346 µs

    Dual input with test pulses

    649 µs

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    Note  

    Input signal response time (0 to 1) assumes the debounce filter, test pulse width, and discrepancy time are set to minimum values for the given configuration.

    Input discharge time (1 to 0)

    40 µs

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    Note  

    Input discharge time represents a 30 V to low state voltage threshold crossing. The maximum input discharge time assumes a 3 kΩ external pull-down, 50 m cable length with a capacitance < 180 pF/m.

    Application processing time

    60 µs

    Automatic self-diagnostics test interval

    Temperature fault

    1.01 s

    Other automatic self-diagnostic faults

    160 µs

    User-configurable diagnostic response time

    Overcurrent

    145 µs

    Open circuit

    145 µs

    Test pulse

    340 µs and configured with very light load

    Internal readback

    150 µs and configured with very light load

    External readback

    149 µs

    Dual input discrepancy

    159 µs

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    Note  

    User-configurable diagnostics assume the minimum values for test pulse width, test pulse period, discrepancy time, read back delay, and output line load.

    Output signal response time[1]

    5 μs, maximum

    • 1 Includes delay time from a change in safety processing logic output to the digital output turning off. This does not include the discharge time for the output load.

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