Analog Status Tag Type Properties: I/O Tab
The I/O Tab includes properties used to identify and establish a connection to the communication driver tag being used to exchange data with your physical I/O device (e.g. PLC or RTU), or to the polling driver responsible for determining the order and rate at which data polls will occur.
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Select the communication driver tag from which data will be read.
The tag button to the right of the field opens the tag browser, from which you can either select an existing communication driver tag or add a new one. The X button will clear the field. Right-clicking on a tag in the field will open a dialog from which you can the driver`s properties.
Provide the address within I/O device from which this tag is to read data. This value must match the configuration of your PLC or RTU hardware.
The addressing system for each of the drivers that come with VTS is provided in the Communication Driver Tags section of this guide.
Provide the frequency, measured in seconds, that the I/O device should be scanned for new data.
If set, then the address field becomes optional. This field provides a means of reading values as recorded by a data logger.
If both the address and the history address are provided, then the address will be polled for data at the interval set by the Scan Rate, but the values read from the data logger will overwrite the values logged by this tag when it is updated.
The history address takes the form DLx:y where 'DL' represents a data logger, x is the data logger address (from 1 to 16) and y is the field number in the logger to be read (from 1 to 8).
Further information on reading history information can be found in the topic SCADAPack History Read
Sets the time between polls of the history data logger. If a History address has been set, but this field is left blank, then it will default to the value set in the Scan Rate field. The recommended value for this field is 60 seconds. Lesser values may cause communications to slow down.
Provide units of measure that the input data represents. Possible values for this field include "rpm" "degrees C", "%", etc.
The value of an analog status tag is automatically logged on change. The deadband range, specified in the defined engineering units, allows you to set a minimum amount by which the input data must change before a new value is written to the log file.
This allows you to dampen out minor value fluctuations, reducing the size of the log file by excluding system noise.
This optional field allows you to provide a constant value that will be used instead of input read by the communication driver. It is commonly used when testing a new Analog Input tag when application is not attached to a live data source. Tags that are using manual data are marked on screen by a flashing exclamation mark.