This is an old revision of the document!
Expressions
Within the configuration of an ezeio, mathematical expressions are used to produce a value/result for “Fields”, “Alarms” and “Conditions”. This powerful tool can produce mathematical and logical results using multiple constants and/or variables from the available resources on an ezeio. Expressions can be as simple as the constant “1” to indicate True/ON or as complex as necessary.
Simple example
Purpose - Show the value of register 8 on device 2:
r(2,8)
Complex example
Purpose - Low oil pressure siren (during work schedule)
Logic - If oil pressure is less than 25 and RPM is greater than 600 and hour is between 06:00 and 17:00
Enter the following in the “Field” relate to an output register
r(3,4)<25 && r(3,3)>600 && hour()>=6 && hour()<17
Functions & Operators
Many of the valid functions and operators will be familiar to you, such as +, -, >, <, and =. Others come from advanced mathematics and logic, such as sin(), tan(), ||, and &&. Another category relates specifically to eze System terms and functions, such as Day() and K2F().
Syntax
The syntax structure of eze System expressions follows common mathematical and logic standards for precedence and functional format.
For example, 2+3*4 equals 2+(3*4) or 14, since multiplication takes precedence over addition.
Boolean logic
Any value greater than 0 is considered 'true'.
0 and all negative values are considered 'false'.