IDEC MicroSmart - Manual (Page 194)

7: B ASIC I NSTRUCTIONS
7-10 « FC4A M ICRO S MART U SER ’ S M ANUAL »
CNT, CDP, and CUD (Counter)
Three types of counters are available; adding (up) counter CNT, dual-pulse reversible counter CDP, and up/down selection
reversible counter CUD. A total of 32 counters (all-in-one 10-I/O type CPU module) or 100 counters (other CPU modules)
can be programmed in a user program. Each counter must be allocated to a unique number C0 through C31 or C99.
The valid operand range depends on the CPU module type. For details, see pages 6-1 and 6-2.
The preset value can be 0 through 65535 and designated using a decimal constant or data register.
CNT (Adding Counter)
When counter instructions are programmed, two addresses are required. The circuit for an adding (UP) counter must be
programmed in the following order: reset input, pulse input, the CNT 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.
Counter Allocation Number Preset Value
CNT (adding counter) C0 to C99
Constant: 0 to 65535
Data registers: D0 to D1299
D2000 to D7999
CDP (dual-pulse reversible counter) C0 to C99
CUD (up/down selection reversible counter) C0 to C99
Ladder Diagram
I2
Reset Input I0
ON
OFF
Pulse Input I1
ON
OFF
Counter C0
ON
OFF
Timing Chart
Output Q0
ON
OFF
1
Input I2
• • •
C0
2 3 4 5 6
ON
OFF
CNT C0
5
I1
Reset
Pulse
Instruction Data
LOD
LOD
CNT
LOD
AND
OUT
I0
I1
C0
5
I2
C0
Q0
Program List
I0
• The same counter number cannot be programmed
more than once.
• While the reset input is off, the counter counts the lead-
ing edges of pulse inputs and compares them with the
preset value.
• When the current value reaches the preset value, the
counter turns output on. The output stays on until the
reset input is turned on.
• When the reset input changes from off to on, the cur-
rent value is reset.
• When the reset input is on, all pulse inputs are ignored.
• The reset input must be turned off before counting may
begin.
• When power is off, the counter’s current value is held,
and can also be designated as “clear” type counters
using Function Area Settings (see page 5-4).
• Counter preset and current values can be changed
using WindLDR without downloading the entire pro-
gram 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 reset input is off.
• When the preset or current value is changed during
counter operation, the change becomes effective imme-
diately.
• For the data movement when changing, confirming,
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.
• The preset value 0 through 65535 can be designated
using a data register D0 through D1299 or D2000
through D7999; then the data of the data register
becomes the preset value. Directly after the CNT
instruction, the OUT, OUTN, SET, RST, TML, TIM,
TMH, or TMS instruction can be programmed.
CNT C28
D5
I1
Reset
Pulse
I0 Q0
Q0