Internal Variables and Expressions

In the ComfileHMI, a Internal variable refers to a named location in the ComfileHMI hardware's memory.

If a Internal variable is used without first being declared, it will be implicitly declared and available for use immediately.

• All variables are global, so they must be given unique names, and can be used on any screen.
• Variables can only store numeric values. Integers, floating point, and even 64-bit integers are supported).
• Variables names are case-sensitive and support Unicode, so variable names can be expressed in any language.
• Variable names cannot begin with numeric digits; they must begin with a letter or an underscore character. Variables names should not contain spaces.
  • A good example for a motor status variable could be Motor1
  • 123abc is invalid because it begins with a numeric digit
  • Motor Status is invalid because it contains a space

A list of variables in use can be obtained from Comfile Studio's main menu: Project→View Addresses and Variables in Use.

String variables were added in a subsequent version of Comfile Studio. They are declared and used with a $ prefix. For example $a="hello".

Internal memory is a specific memory region in the ComfileHMI hardware. It is volatile, so it will be erased when the ComfileHMI hardware is powered off.

There are 1024 memory locations (indexed 0~1023) that can be written and read to. They can store 64-bit integers and double-precision floating point values.

• set_mem(index, value) : Writes value to internal memory at index.
• mem(index) : Reads the value current stored in internal memory at index.

Multiple values can be stored adjacently in internal memory by passing multiple value arguments to the set_mem function.

• set_mem(index, value1, value2, …, valueN)

See the internal memory functions.

Conditional expressions provide the ability to compare variables.

<, <=, ==, >=, >, != operators are supported. They are identical to the comparison operators used in the C programming language.
&& and || are boolean AND and boolean OR operators respectively.

(Example)
MotorStatus > 1
Heater1 == 0 ⇐ true if Heater1 is equal to 0
Heater1 != 0 ⇐ true if Heater1 does not equal 0

+, -, *, /, and % operators are supported for performing math on variables. They are identical to the arithmetic operators used in the C programming language.

(Example)
MotorStatus + 1

>>, <<, |, and & operators are supported for bitwise operations. They are identical to the bitwise operators used in the C programming language.

(Example)
(bits >> 2) & 1

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