Status
The CPO 10 application supports optional status inputs which provide feedback indicating whether the chillers, isolation valves, pumps, and cooling towers are on or off. In some cases, the status is only monitored. In other cases, the status can be compared to the command and the device may become locked out if the command and status mismatch for a user-defined period of time.
Setup, Delay, and Maintenance Switch
The Setup Input Modes of Operation table describes the four Setup input modes of operation. The setup determines what is done with the comparison between the command and status, or if it uses the status. The Additional Inputs table provides descriptions of the Delay and Maintenance Switch.
| Mode of Operation | Description |
|---|---|
| None | The device does not have any status input, and the module routes the command through the primitive to the OffOn output. The primitive does not check for a mismatch between the command and status inputs. |
| Status | The device does have status feedback, and the Device Status input is used for the OffOn output. The primitive does not check for a mismatch between the command and status inputs. |
| Automatic Restart | The device does have status feedback, and the Device Status input is used for the OffOn output. The primitive checks for a mismatch between the command and status. The primitive disables the device if the command and status are mismatched longer than the delay times. This mode allows the primitive to correct itself when the mismatch is corrected. The primitive has properties for the maximum number of retries allowed before user intervention is required; for example, Reset. It also has a Retry Interval property for setting the time to wait after a retry before attempting to start the device again. |
| Manual Restart | The device does have status feedback, and the Device Status input is used for the OffOn output. The primitive checks for a mismatch between the command and status. The primitive disables the device if the command and status are mismatched longer than the delay times. This mode requires manual reset to enable the device. |
| Input | Description |
|---|---|
| Output Delay | The maximum amount of time the status and command may mismatch before the device is disabled. This forgiveness time is used when a device is turning on or a device is turning off. |
| Lost Status Delay | This input is similar to the Output Delay, but it is used after the device was commanded on, status was confirmed, but later lost. For Chiller Interlocks, this input may be set to a longer time than the output delay to allow a chiller to recover from low load recycle without disabling the chiller, but must be short enough to bring on a new chiller if the chilled water temperature begins to rise. For Pumps and towers, this time delay should be the same as the Output Delay. |
| Maintenance Switch | This input provides a Binary Input to disable or enable the controlled device. |
Unit Reset Switch
The application has a unit reset input if any alarms or interlocks require a manual reset. At selection time, the user has the option to select either a hardware or network input for unit reset.