You can use them as general booleans in your own programs, they can be parts of certain operations (ie: the CY (carry) flag is used on arithmetic operations which result in a carry - other flags are used to indicate overflows or div/0 errors, etc).Д®dit again : (to answer extended question).ДЄ basic timer's completion flag is a contact with its number. You would use differentials in cases where you wanted to perform an action the moment a given condition changes.ДЇlags can be used for almost anything. If the timer's number is, say T100 then you can use T100 as a contact in another rung of logic - it will be true when the timer's execution conditions are TRUE and the timer has expired.Дifferentials (UP/DOWN) are special flags which are true for only one PLC scan (ie: they are true for one execution cycle only) when their input conditions change from FALSE to TRUE (ie:OFF to ON) for UP differentials, and TRUE to FALSE (ie:ON to OFF) for DOWN differentials.

When the value reaches zero the timer's flag turns ON to indicate that it has expired. When the timer turns on it will begin counting and the PV (process value) will start from 300 and count down. If you use a BCD type 100ms timer and assign its SV (setpoint value) a BCD value of 300 then you have created a timer with a 30 second limit (300 x 100ms). These show time diagrams of most of the instructions and how each of the parameters and flags operate.ДЇor example, a basic timer (TIM) works by assigning it a value. If you have CX-Programmer, a much better place to get information is the Instruction Reference (Help -> Instruction Reference -> yourPLC). Think of flags as interchangeable with the term 'bit', 'boolean', etc. PLCs are like any program - data is stored as different types.

Instruction cx programmer