IDEC MicroSmart User Manual
Page 196
7: B
ASIC
I
NSTRUCTIONS
7-12
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CUD (Up/Down Selection Reversible Counter)
The up/down selection reversible counter CUD has a selection input to switch the up/down gate, so that 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 C99, followed by a counter
preset value from 0 to 65535.
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
I0
I1
CUD
C2
500
I2
Preset Input
Pulse Input
U/D Selection
I3
C2
Instruction
Data
LOD
LOD
LOD
CUD
LOD
AND
OUT
I0
I1
I2
C2
500
I3
C2
Q2
Program List
• The same counter number cannot be pro-
grammed more than once.
• The preset input must be turned on initially so
that the current value returns to the preset
value.
• The preset input must be turned off before
counting may begin.
• 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.
• The counter output is on only when the cur-
rent value is 0.
• After the current value reaches 0 (counting
down), it changes to 65535 on the next count
down.
• After the current value reaches 65535 (count-
ing up), it changes to 0 on the next count up.
• When power is off, the counter’s current
value is held, and can also be designated as
“clear” type counters using the Function Area
Settings (see page 5-4).
• Counter preset and current values can be
changed using
WindLDR
without download-
ing the entire program to the CPU again.
From the
WindLDR
menu bar, select Online >
Monitor
, then select Online > Point Write.
To change a counter preset value, specify the
counter number with a capital C and a new
preset value. To change a counter current
value, specify the counter number with a
small c and a new current value while the
counter preset input is off.
• When the preset or current value is changed
during counter operation, the change
becomes effective immediately.
• For the data movement when changing, con-
firming, and clearing preset values, see page
7-13. Preset values can also be changed and
changed preset values can be confirmed using
the HMI module. See pages 5-35 and 5-36.
500 500
Preset Input I0
ON
OFF
Pulse Input I1
ON
OFF
U/D Selection
ON
OFF
Timing Chart
Counter C2
ON
OFF
500 501 502 501
Counter C2 Value
500 499
0
1
• • •
• • •
Q2
Valid Pulse Inputs
The reset or preset input has priority over the pulse input.
One scan after the reset or preset input has changed from on
to off, the counter starts counting the pulse inputs as they
change from off to on.
Reset/Preset
ON
OFF
Pulse
ON
OFF
More than one scan
time is required.
Valid
Invalid
Valid
Input I2
Caution
• For restrictions on ladder programming