Handling Of High Speed Counters - Mitsubishi Electric MELSEC FX3U Programming Manual

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
Restriction 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.
• Since the FX
only one of them may be used in operation. If both input terminals are used, intended operation is not
enabled because the inputs of the FX
4.7.3

Handling of high speed counters

1. 1-phase 1-count input
X010
M8235
X011
X012
C235
X010
M8244
X011
X012
C244
Operation example
The counter C235 shown above operates as follows:
X010 Up counting
X011
Reset input
X012
Start input
X000
Counting
input
3
C235
2
Current
1
value 0
When output has
already been activated
C235 output contact
When counting with input X000, C235 executes up-count or down-count as an 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.
112
-4HSX-ADP and FX
3U 3UC
3U
Down/up count
Reset
RST C235
K-5
Down/up count
Reset
RST C244
D0(D1)
Set value is (D1, D0)
Down counting
5
4 4
3
2
1
0
−1
−2
−3
−4
−5
4.7 High Speed Counter [C] (FX3U/FX3UC PLC)
PLC main unit share the same assigned input terminal numbers,
-4HSX-ADP and PLC main unit operate in an "OR" relationship.
• 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-count or up-count 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 C244 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-count or up-count when M8235 to
M8245 turns ON or OFF.
Up counting
0
−3
−4
−5
−6 −6
−7 −7
−8
4 Devices in Detail