IDEC MICROSmart FC6A Series Ladder Programming Manual page 110

4: B I
ASIC NSTRUCTIONS
CUD (Up/Down Selection Reversible Counter)
The up/down selection reversible counter CUD has a selection input to switch the up/down gate, so the three inputs are required.
The circuit for an up/down selection reversible counter must be programmed in the following order: preset input, pulse input, up/
down selection input, the CUD instruction, and a counter number C0 through C511, followed by a counter preset value from 0 to
65,535.
The preset value can be designated using a decimal constant or a data register. When a data register is used, the data of the data
register becomes the preset value.
Ladder Diagram
Preset Input
CUD C2
500
I0
Pulse Input
I1
U/D Selection
I2
I3 C2 Q2
• The preset input must be turned on initially so that the current value returns to the preset value.
• The up mode is selected when the up/down selection input is on.
• The down mode is selected when the up/down selection input is off.
• After the current value reaches 0 (counting down), it changes to 65,535 on the next count down.
• After the current value reaches 65,535 (counting up), it changes to 0 on the next count up.
• The counter output is on only when the current value is 0.
Timing Chart
ON
Preset Input I0
OFF
ON
Pulse Input I1
OFF
U/D Selection
ON
Input I2
OFF
Counter C2 Value
ON
Counter C2
OFF
4-14
Program List
Instruction
LOD
LOD
LOD
CUD
LOD
AND
OUT
• • •
500 501 502 501 500 499
• • •
FC6A S MICROS
ERIES MART
Data
I0
I1
I2
C2
500
I3
C2
Q2
0 1 500 500
L P M
ADDER ROGRAMMING
FC9Y-B1726
ANUAL