[General]TagStartDigit

Allows you to use tags. tag items, or equipment names that have a number as the first digit.

Using a number as the first digit of a tag is not a good engineering practice. Tags starting with numbers are not supported by modern programming languages and they are not allowed in the industrial control systems standard IEC 1131-3. This is because it creates confusion when tags are used in complex expressions. This was not a problem with older simpler systems when you could only get the value of a tag.

This functionality is supported primarily for users converting large existing databases to Plant SCADA.

Only variable tags and Cicode variables can start with numbers. You cannot start labels or label arguments with numbers.

As Plant SCADA supports several types of numbers there can be confusion with tags starting with number clashing with the special types of numbers. For example the following may look like tags:

When [General]TagStartDigit is set to 0 (zero), the above tags are treated as valid numbers.

However, if you have [General]TagStartDigit set to 1, and you have these types of numbers in your project, you must observe the following conventions:

• Numbers such as 0E12334 must contain a decimal point to distinguish them from tags, For example, 0E23 is a tag and 0.E23 is a float when the [General]TagStartDigit parameter is enabled.

• Numbers such as 0O01234567 (that's an O as in Orange), 0X01234, and 0B01, must use lowercase for alpha characters, and any potentially conflicting tags must use uppercase. For example, 0x10 will be considered a hex number, and 0X10 a tag. Note that if you use lower case to denote a number, but the number is illegal, it will be considered a tag. For example:

Because of the above considerations you cannot define tags which look like valid numbers. For example 0x123 will be treated as a number, not a tag. You should always use upper case for tags starting with a number and the tag must contain at least one alpha (A..Z) or underscore (_) character.

Also you cannot define numbers which look like tags. When TagStartDigit=0, then 0X123 will be treated as a hex number. When [General]TagStartDigit=1, 0X123 will be treated as a tag. This can cause problems if you have existing Cicode from older projects which has numbers defined this way. When you switch this option on, you may find you will get the "Tag not found" compiler error. This will occur because Plant SCADA will think that some of your numbers are tags and so try to find them in the Tag database.

Note: CitectVBA does not recognize Plant SCADA variable tags which are named with an initial digit (0-9).

Allowable Values:

• 0 - (Do not allow tags with number as first digit)

• 1 - (Allow tags with number as first digit)

Default Value:

0

See Also

General Parameters