92
FX
3U
/FX
3UC
Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
4 Devices in Detail
4.7 High Speed Counter [C]
Prohibition to overlap input numbers
• Inputs X000 to X007 are used for high speed counters, input interrupt, pulse catch, SPD/ZRN/DSZR/DVIT
instructions and general-purpose inputs. When assigning functions, there should be no overlap between
those input terminals.
For example, when C251 is used, X000 and X001 are occupied. As a result, "C235, C236, C241, C244,
C246, C247, C249, C252 and C254", "input interrupt pointers I000 and I101", "pulse catch contacts M8170
and M8171" and "SPD, ZRN, DSZR and DVIT instructions using X000 and/or X001" cannot be used.
• Though a same input number is assigned to an input terminal of FX
3U
-4HSX-ADP and terminal of FX
3UC
PLC main unit both use either one of those input terminals. If both input terminals are used, intended
operation is not enabled because the input of FX
3U
-4HSX-ADP and the input of FX
3UC
PLC main unit
operate in "OR" relationship.
4.7.3
Handling of high speed counters
1. 1-phase 1-counting input
•
C235 counts "OFF
→
ON" of the input X000 while X012
is ON.
•
When X011 turns ON and then RST instruction is
executed, C235 is reset.
•
The counting direction of the counters C235 to C245 is
switched to down-counting or up-counting when M8235
to M8245 turns ON or OFF.
•
C244 immediately starts counting when the input X006
turns ON while X012 is ON. The counting input is X000.
In this example, the set value is indirectly specified by
the contents of data registers (D1 and D0).
•
A high speed counter can be reset using X011 in a
sequence as shown in the figure, but it is immediately
reset without any program when X001 is closed. So a
program with X011 is not necessary.
•
The counting direction of the counters C235 to C245 is
switched to down-counting or up-counting when M8235
to M8245 turns ON or OFF.
Operation example
The counter C235 shown above operates as follows:
By the counting input X000, C235 executes up-counting or down-counting as interrupt.
• When the current value of a counter increases from "
−
6" to "
−
5", the output contact is set. When the
current value decreases from "
−
5" to "
−
6", the output contact is reset.
X010
M8235
Down/up counting
X011
X012
C235
K-5
RST
C235
Reset
X010
M8244
Down/up counting
X011
X012
C244
D0(D1)
RST
C244
Reset
Set value is (D1, D0)
X010
X011
X000
C235
Current
value
C235 output contact
Up counting
Down counting
Up counting
0
1
2
3
4
5
4
3
2
1
0
−
1
−
2
−
3
−
4
−
5
−
6
−
7
−
8
When output has been
already activated
−
7
−
6
−
5
−
4
−
3
0
X012
Reset input
Start input
Counting
input