The Equipment Interlock module enables equipment for use within a Control Sequence. The Equipment Interlock module can only exist within a Control Sequence or Control Activity within a Control Sequence. The purpose of the Equipment Interlock module is to remove equipment from service when either the maintenance switch is set to Disable or a mismatch exists between the Device Status and Command after a delay time expires. This module has four modes of operation: None, Status, Automatic Restart, and Manual Restart.
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None: The device does not have any status input, and the module routes the command through the module to the OffOn output. The module does not check for a mismatch between the command and status inputs.
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Status: The device does have status feedback, and the Device Status input is used for the OffOn output. The module does not check for a mismatch between the command and status inputs.
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Automatic Restart: The device does have status feedback, and the Device Status input is used for the OffOn output. The module checks for a mismatch between the command and status. When the property Check Command On Mismatch is true, the module identifies a mismatch only when the command input is on. When the property is false, the module identifies a mismatch between command and status when the command input is either on or off. The module disables the device if the command and status are mismatched longer than the delay times. This mode allows the module to correct itself when the mismatch is corrected. The module has properties for the maximum number of retries allowed before user intervention is required (for example, Reset). The Equipment Interlock also has a Retry Interval property for setting the time to wait after a retry before attempting to start the device again.
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Manual Restart: The device does have status feedback, and the Device Status input is used for the OffOn output. The module checks for a mismatch between the command and status. When the property Check Command On Mismatch is true, the module identifies a mismatch only when the command input is on. When the property is false, the module identifies a mismatch between command and status when the command input is either on or off. The module disables the device if the command and status are mismatched longer than the delay times. This mode requires manual reset to enable the device.
The module’s Usage output is set to Unavailable, Available, or On. The value of Usage depends on whether the device is enabled or disabled, and the device status. For instance, if the device is disabled, its Usage is Unavailable. If the device is enabled but off, its Usage is Available, and if the device is enabled and on, the Usage is On.
You cannot view and modify the modules in this group’s logic.
Figure 1 and Figure 2 graphically convey the behavior of the Equipment Interlock module.
