Rockwell Automation 1761 MicroLogix 1000 Programmable Controllers User Manual
Page 226
Preface
MicroLogix 1000 Programmable Controllers User Manual
12–12
When the low preset is reached, the:
•
LP bit is set.
•
High-speed counter interrupt file (program file 4) is executed if the interrupt is
enabled. The IL bit is set and the IH, IV, and IN bits are reset.
An overflow occurs when the hardware accumulator transitions from
+
32,767 to
–32,768. When an overflow occurs, the:
•
OV bit is set.
•
High-speed counter interrupt file (program file 4) is executed if the interrupt is
enabled. The IV bit is set and the IH, IL, and IN bits are reset.
An underflow occurs when the hardware accumulator transitions from –32,768 to
+
32,767. When an underflow occurs, the:
•
UN bit is set.
•
High-speed counter interrupt file (program file 4) is executed if the interrupt is
enabled. The IN bit is set and the IH, IL, and IV bits are reset.
The following tables summarize what the input state must be for the corresponding
high-speed counter action to occur:
Bidirectional Counter (Pulse/direction)
Input State
H g -Speed
Input Count
(I/0)
Input
Direction
(I/1)
Input Reset
(I/2)
Input Hold
(I/3)
HSC Rung
High-Speed
Counter Action
Turning
Off-to-On
Off
NA
NA
True
Count Up
Turning
Off-to-On
On
NA
NA
True
Count Down
NA
NA
NA
NA
False
Hold Count
Off, On, or
Turning Off
NA
NA
NA
NA
Hold Count
NA (Not Applicable)