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DATA VALUES
CRIMSON USER MANUAL - MODULAR CONTROLLER
WRITING EXPRESSIONS
You will recall from the earlier sections of this manual that many fields within Crimson are
configured as what are called expression properties. You will further recall that these fields
are configured by means of a user interface element similar to that shown below…
In many situations, you will be configuring these properties to be equal to the value of a tag,
or to the contents of a register in a remote communications device, in which case your
selection will be made simply by clicking the appropriate option on the drop-down menu, and
then selecting the required item from the resulting dialog box.
There will be situations, though, when you want to make a property dependent on a more
complex combination of data items, perhaps using some math to combine or compare their
values. Such eventualities are handled via what are known as expressions, which can be
entered in the property’s edit box whenever General mode is selected via the drop-down.
DATA VALUES
All expressions contain at least one data value. The simplest expressions are thus references
to single constants, single tags or single PLC registers. If you enter either of the last two
options, Crimson will simplify the editing process by automatically changing the property
mode as appropriate. For example, if you enter a tag name in General mode, Crimson will
switch to Tag mode, and show the tag name in the selection field.
CONSTANTS
Constants represent—not surprisingly—constant numbers or strings.
INTEGER CONSTANTS
Integer constants represent a single 32-bit signed number. They may be entered in decimal,
binary, octal or hexadecimal as required. The examples below show the same number entered
in the four different number bases…
BASE
EXAMPLE
Decimal 123
Binary
0b1111011
Octal 0173
Hexadecimal
0x7B
The ‘U’ and ‘L’ suffixes supported by earlier versions of software are not used.
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