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The function references that follow are meant to be an aid for programming. There are some notes that should be observed, especially because this list discusses instructions for more than one type of PLC.
· The following function descriptions are for both the Micrologix and PLC-5 processor families. There are some differences between PLC models and families.
· Many flags in status memory can be used with functions, including;
Counter memory instructions can share the same memory location, so some redundant bits are mentioned here.
Most file instructions will contain Mode options. The user may choose these with the implications listed below.
All - All of the operations will be completed in a single scan when the input to the function is edge triggered. Care must be used not to create an operation so long it causes a watchdog fault in the PLC
Incremental - Each time there is a positive input edge the function will advance the file operation by one.
'number' - when a number is supplied the function will perform that many iterations while the input rung is true.
The following table describes the arguments and return values for functions. Some notes are;
· 'immediate' values are numerical, not memory addresses.
· 'returns' indicates that the function returns that data value.
· numbers between '[' and ']' indicate a range of values.
· values such as 'yes' and 'no' are typed in literally.