Allen-Bradley MicroLogix 1200 Reference Manual page 85

Count Direction (DIR)
Description Address Data Format HSC Modes
DIR - Count HSC:0/DIR bit
Direction
(1) For Mode descriptions, see HSC Mode (MOD) on page 5-16.
The DIR (Count Direction) status flag is controlled by the HSC sub-system.
When the HSC accumulator counts up, the direction flag is set (1).
Whenever the HSC accumulator counts down, the direction flag is cleared
(0).
If the accumulated value stops, the direction bit retains its value. The only
time the direction flag changes is when the accumulated count reverses.
This bit is updated continuously by the HSC sub-system whenever the
controller is in a run mode.
Mode Done (MD)
Description Address Data Format HSC Modes
MD - Mode HSC:0/MD bit
Done
(1) For Mode descriptions, see HSC Mode (MOD) on page 5-16.
The MD (Mode Done) status flag is set (1) by the HSC sub-system when
the HSC is configured for Mode 0 or Mode 1 behavior, and the
accumulator counts up to the High Preset.
Count Down (CD)
Description Address Data Format HSC Modes
CD - Count Down HSC:0/CD bit
(1) For Mode descriptions, see HSC Mode (MOD) on page 5-16.
The CD (Count Down) bit is used with the bidirectional counters (modes
2 to 7). If the CE bit is set, the CD bit is set (1). If the CE bit is clear, the
CD bit is cleared (0).
Using the High-Speed Counter
(1) Type User Program Access
0 to 7 status read only
Type User Program Access
(1)
0 or 1 status read/write
(1) Type User Program Access
2 to 7 status read only
Publication 1762-RM001C-EN-P
5-15