How To Use 2-Phase 2-Counting Input Counters C251 To C255 For 4-Edge Counting - Mitsubishi Electric MELSEC-Q Structured Programming Manual

FXCPU Structured Programming Manual
[Device & Common]
2.7.8

How to use 2-phase 2-counting input counters C251 to C255 for 4-edge counting

2-phase 2-counting input counters C251 to C255 usually executes 1-edge counting, but can be used for 4-
edge counting by the programs shown in the table below.
FX /FX /FX
0S 0 0N
function.
Counter No.
C251
C252
C253
C253(OP)
C254
C255
82
/FX /FX /FX /FX
1S 1N 1NC U
When using 2-phase 2-counting input counter for 4-edge counting
M8000
M8198
EN
CCoil
CC251
K
CValue
M8000
M8198
EN
CCoil
CC252
K
CValue
M8000
M8199
EN
CCoil
CC253
K
CValue
M8000
M8199
M8388
M8392
EN
CCoil
CC253
K
CValue
M8000
M8198
EN
CCoil
CC254
K
CValue
M8000
M8199
EN
CCoil
CC255
K
CValue
/FX /FX /FX /FX
2C 2N 2NC 3S
OUT_C_32
ENO
OUT_C_32
ENO
OUT_C_32
ENO
OUT_C_32
ENO
OUT_C_32
ENO
OUT_C_32
ENO
2 Devices in Detail
2.7 High Speed Counter [C]
/FX /FX PLCs do not support this
3G 3GC
Description
1-edge counting (before change)
Phase A
+1
Phase B
Up-counting
Phase A
-1
Phase B
Down-counting
4-edge counting (after change)
+1 +1 +1 +1 +1
Phase A
Phase B
+1 +1 +1 +1
Up-counting
-1 -1 -1 -1 -1
Phase A
Phase B
-1 -1 -1 -1
Down-counting
+1
-1