Topic: DMD0468
LIFORESET - Reset LIFO Queue
The Reset LIFO Queue (LIFORESET) instruction is used to clear all of the flags and status fields of a LIFO Queue structure and optionally clear the contents of the User Block where the LIFO Queue stores its data.
Parameters:
Note: Use the F9 key or click the 'three dot box' at the right edge of the parameter field to open the Default Element Selection Tool (the Element Picker or the Element Browser) or use the Down-Arrow key (Auto-Complete) on any parameter field to see a complete list of the memory locations that are valid for that parameter of the instruction.
Queue Control Structure is the data structure that controls this LIFO Queue. This should be the same Queue Control Structure that is used in the corresponding LIFOLOAD / LIFOUNLOAD instructions.
Enable the Clear User Block option to clear the contents in all locations of the selected user-created data block. It is not necessary to clear the User Block; any existing data in the User Block can remain without causing any problems. The critical action of the LIFORESET is to ensure the Queue Structure is initialized as an empty LIFO stack. This LIFORESET instruction should reference the same User Block that is used in the corresponding LIFOLOAD / LIFOUNLOAD instructions.
Reset on Input Leg selects which power-flow conditions will cause this instruction to reset the LIFO Queue:
- Edge Triggered
means that each time the input ladder logic
transitions from OFF to ON, the instruction will reset the LIFO Queue.
- Power flow enabled means that each scan the input ladder logic is ON, the instruction will reset the LIFO Queue. This is the proper selection if this instruction is used within a loop (e.g. For / Next) because instructions inside loops cannot detect rising edges.
Status Display:
See Also:
LIFOLOAD - Load Last In / First Out
LIFOUNLOAD - Unload Last In / First Out
LIFORESET - Reset LIFO Queue
Related Topics:
FIFOLOAD - Load First In / First Out
FIFOUNLOAD - Unload First In / First Out
Example:
