csmstr - Omega Engineering

ALL ABOUT TAGS
CRIMSON USER MANUAL - MODULAR CONTROLLER
Integer tags represent 32-bit signed numbers. These tags can store values between
–2,147,483,648 and +2,147,483,647. Even if a tag is mapped to a PLC register
which contains only 16 bits of data, Crimson performs its internal operations at
the higher level of precision to ensure large intermediate values can be handled
with ease.
Multi tags represent numeric values that correspond to a number of distinct states.
Thus, while an integer might represent a tank level, a multi tag will represent,
say, one of three states of a machine, such as Stopped, Running or Paused. The
distinction is obvious when you consider that a multi tag is displayed as one of a
set of strings, while an integer is displayed as a number.
Real tags represent 32-bit single precision floating-point numbers. These tags can
store values between ±10 -38 and ±10 +38 with a precision of about 7 significant
figures. While it is seldom necessary to use real tags to represent physical
quantities—which typically have more tightly defined ranges—they are useful for
performing statistical operations or other math functions.
String tags represent an item of text made up of a number of characters. They are
used to store such things as recipe names, or to process data received using Raw
Port device drivers. Strings cannot be mapped to PLC registers, but can be used
to store such data within the Master itself.
TAG COLORS
The color of the tag depends of its family and mapping with a communication device. The
table below shows the different colors by family and access for an integer tag. The same color
scheme is used on all tag types; only the symbol is then different as shown above.
VARIABLE FORMULA ARRAY
Internal Blue Olive Purple
Mapped as Read only Green N/A Green
Mapped as Read/Write
or Write Only
Red N/A Red
WHY USE TAGS?
Given all these various options, you may wonder why you would want to use tags in the first
place? After all, Crimson allows you to directly place a module or PLC register on a display
page, so you can in fact configure a simple database without ever opening the Data Tags icon.
The basic answers are as follows…
• Tags allow you to name data items, so you know which data item within the PLC
you are referring to. Further, if the data in the PLC moves or if you decide to
switch to an entirely different family of PLC, you can simply re-map the tags,
and avoid having to make any other changes to your database.
PAGE 104
http://www.redlion.net/controller