The name of the equipment associated with the variable tag. Select a name from the drop-down list of existing equipment definitions, or enter a name.

There is a limit of 254 characters across the Equipment and Item Name fields, including any separating periods (.).

You can use any name for a tag (79 characters) provided it follows the tag name syntax rules and isn't the same as the name of a Cicode function within the project or any included projects (see Tag Name Reserved Words for a list of restrictions on naming).

If you have many tags, use a naming convention (see Using Structured Tag Names). This makes it easier to find and debug your tags. When the tag name is referenced on a graphics page, Cicode, etc., it can be used with or without a specific tag element or item.

If you are using distributed serversIf your plant consists several sections or systems, you can assign a cluster to each individual section, and then monitor all sections using one control client. Don't use distributed servers to split up a single section or process into discrete areas. A single cluster system with distributed processing would be better used here since it would not be hampered by the maintenance overhead of a distributed server system (such as extra project compilations, and so on)., the name needs to be unique to the cluster (for example, you cannot have the same variable tag name in more than one cluster).

Note: Citect SCADA will automatically resolve tags without a cluster context specified if every tag name in the project is unique. See Clusters.

The name of the cluster that runs the variable tag. This field needs to be defined if your project has more than one cluster.

You can leave this field blank in a multi-cluster system if cluster replication is enabled (see the parameter [General]ClusterReplication).

The name of the I/O device where the variable is stored (31 characters). If using I/O device redundancy, you need to specify the primary I/O device name here, not the standby.

Note: Avoid changing the tag's I/O device name from this FORM as the variable.dbf will not be updated. If you do change the tag's I/O device name you will need to clear the tag's reference fields.

The type of I/O device variable (16 characters). I/O devices support several data types that are used to exchange data with Citect SCADA. Because of the lack of an industry standard, many I/O device manufacturers use individual naming conventions for their I/O device variables. However, every variable corresponds to one of the tag data types.

Note: If you do not specify a range for your tag, then an out of range alert message will be generated if you write a value which is outside the range of the type.

You need to specify the correct data type that corresponds to the data type of the I/O device variable you are configuring. Each data type has a unique address format. You need to use this format when you are specifying the address of the variable (as the Address property).

You will want to verify that you only use data types that are valid for your I/O device. If you do not specify a data type, the variable will be treated as 16-bit integer.

Citect SCADA supports concatenation of I/O device registers. For example, you can define a real data type (in Citect SCADA) as two contiguous int data types (in the I/O device). Citect SCADA reads across the boundary of the two INTs and returns a REAL.

If you use concatenation of registers, the address of the variables needs to be on odd boundaries or even boundaries. You cannot mix address boundaries. For example, V1, V3, V5 are valid addresses.

Be careful when using this feature: the I/O device needs to maintain the integrity of the second register. (If the I/O device writes to the second int, the value of the real could be corrupted.) The structure of some I/O devices might not support this feature, and might therefore behave unpredictably.

The register address in the I/O device where the variable is stored (254 characters). The format and prefix of an address will depend on the protocol configured for the I/O device, which can be determined by checking the Protocol field on the I/O devices view in Citect Studio.

Any useful comment (254 characters).

(11 characters). A deadband allows the value of a variable tag to fluctuate within a defined threshold without updates being sent through the system. This may be useful if a tag produces many small, insignificant value changes. The threshold is represented as a percentage of the tag's engineering range. The default value is 0 (zero), which captures every value change.

For example, if a variable tag has an engineering range of zero to 10000, a deadband of 1 would mean a change in value would have to be greater than 100 (or 1 percent of the range) to be recognized. If the current value was 5600, the tag in the PLC would have to change to a value greater than 5700 or less than 5500 before an update would be sent through the system.

The deadband setting for a variable tag will not apply to an associated trend tag. If a trend tag requires a deadband setting, it should be configured independently in the trend tag properties.

(8 characters.) The engineering units that the value represents (for example %, deg, mm/sec, etc.). This property is optional. If you do not specify engineering units, no engineering units are used.

The unscaled (raw) values (of the variable) that represent the zero point and full scale point for the data (11 characters). The raw values are the values that Citect SCADA reads from the I/O device.