Table Of Contents

Digital Input Configurations

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    Last Modified: May 15, 2018

    Table 1. Single Input
    Fault Input Signal Status
    Low High
    Short to ground Not detected, safe state Not detected, safe state
    Short to Vsup Not detected Not detected
    Open circuit Not detected, safe state Not detected, safe state
    Table 2. Single Input with Test Pulse
    Fault Switch Condition
    Open Closed
    Short to ground (test pulse output channel) Overcurrent fault Overcurrent fault
    Short to Vsup (test pulse output channel) Not detected, safe state Test pulse fault
    Short to ground (input channel) Not detected, safe state Overcurrent fault
    Short to Vsup (input channel) Test pulse fault Test pulse fault
    Open circuit Not detected, safe state Not detected, safe state
    Table 3. Equivalent Dual Input
    Fault Input Signal Status
    Low High
    Short to ground (one channel) Not detected, safe state Discrepancy fault
    Short to ground (both channels) Not detected, safe state Not detected, safe state
    Short to Vsup (one channel) Discrepancy fault Not detected
    Short to Vsup (both channels) Not detected Not detected
    Channels shorted together Not detected Not detected
    Open circuit (one channel) Not detected, safe state Discrepancy fault
    Open circuit (both channels) Not detected, safe state Not detected, safe state
    Table 4. Complimentary Dual Input
    Fault Input Signal Status
    Low High
    Short to ground (one channel) Not detected Discrepancy fault
    Short to ground (both channels) Discrepancy fault Discrepancy fault
    Short to Vsup (one channel) Discrepancy fault Not detected
    Short to Vsup (both channels) Discrepancy fault Discrepancy fault
    Channels shorted together Discrepancy fault Discrepancy fault
    Open circuit (one channel) Not detected Discrepancy fault
    Open circuit (both channels) Discrepancy fault Discrepancy fault
    Table 5. Equivalent Dual Input with Test Pulse
    Fault Switch Condition
    Open Closed
    Short to ground (one or both test pulse output channels) Overcurrent fault Overcurrent fault
    Short to Vsup (one or both test pulse output channels) Test pulse fault Test pulse fault
    Test pulse output channels shorted together Test pulse fault Test pulse fault
    Short to ground (one or both input channels) Not detected, safe state Overcurrent fault
    Short to Vsup (one or both input channels) Test pulse fault Test pulse fault
    Input channels shorted together Test pulse fault Test pulse fault
    Open circuit (one channel) Not detected, safe state Discrepancy fault
    Open circuit (both channels) Not detected, safe state Not detected, safe state
    Table 6. Complimentary Dual Input with Test Pulse
    Fault Switch Condition
    Open Closed
    Short to ground (one or both test pulse output channels) Overcurrent fault Overcurrent fault
    Short to Vsup (one or both test pulse output channels) Test pulse fault Test pulse fault
    Test pulse output channels shorted together Test pulse fault Test pulse fault
    Short to ground (one input channel) Not detected Overcurrent fault
    Short to ground (both input channels) Discrepancy fault Discrepancy fault
    Short to Vsup (one or both input channels) Test pulse fault Test pulse fault
    Input channels shorted together Test pulse fault Test pulse fault
    Open circuit (one channel) Not detected Discrepancy fault
    Open circuit (both channels) Discrepancy fault Discrepancy fault

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