Topic: DMD0176
RSTT - Reset Timer
The Reset Timer (RSTT) instruction is used to programmatically reset a Timer and its associated structure. The Reset Timer instruction is the proper method to reset a TMRAG - Global Accumulating Up Timer.
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.
Timer Struct specifies which Timer number to edit, and by extension, the name of the Timer's associated structure. This can be any of the System-created Timers, or any user-created Timer. The default Memory Configuration contains 255 predefined Timers named T0 through T255.
Termination Scan Behavior:
All Timers - with one exception - have termination logic. This means if the Timer instruction is contained within a Program, a Task, or a Stage, the Timer will automatically be reset any time that Program, Task, or Stage stops executing because of an End Program, End Task, or Disable Stage respectively.
The Global Accumulating Up Timer (TMRAG) instruction does NOT have termination logic, meaning that it will retain it's accumulated time and the state of it's internal flags even if it is contained within a Program, a Task, or a Stage, that is disabled.
Refer to the Help topic on Termination Behavior for detailed information on the programming elements that have termination logic.
Timer Structure Members:
All Timers have an associated structure with fields that can be used in the ladder program. The structure fields are updated whenever the Timer instruction is processed in the PLC scan. The syntax for using them is <Timer structure>.<field name>, for example, T7.Acc.
.Acc (read/write) is a 32-bit signed value that represents the total accumulated time whenever the Timer is enabled. If the Timer is still enabled after the Preset is reached, the .Acc value keeps incrementing to a maximum of 2,147,483,647 ms (596 hrs, 31 min, 23.647s), it does not wrap.
.Done (read-only) will be ON any time the Timer's accumulator value (.Acc) is greater than or equal to the Timer's Preset value.
.Zero (read-only) will be ON any time the Timer's accumulator value (.Acc) is 0.
.Timing (read-only) will be ON if the Timer is enabled, and is NOT being held in Reset by the Reset Input leg or a Reset Timer (RSTT) instruction. Will remain ON after .Done turns ON.
.Reset (read-only) will be ON if the reset (RST) leg's input logic is TRUE, or if the Timer is being reset by a Reset Timer (RSTT) instruction.
.TT (read-only) will be ON if the Timer is enabled, and is NOT being held in Reset by the Reset Input leg or a Reset Timer (RSTT) instruction. Will turn OFF when .DN turns ON.
.EN (read-only) will be ON any time the Timer's input logic is TRUE, and the Timer is NOT being held in Reset by the Reset Input leg or a Reset Timer (RSTT) instruction.
.DN (read-only) will be ON any time the Timer's input logic is ON and it's accumulator value (.Acc) is greater than or equal to the Timer's Preset value.
See Also:
RSTT - Reset Timer
Related Topics:
TMRADOWN - Accumulating Down Timer
TMRAG - Global Accumulating Up Timer
Rung Example:
