FX Series Programmable Controllers Devices in Detail 4
4-28
4.11.4 Availability of High Speed Counters
on FX
2N(C)
PLC’s
The followin
device table outlines the ran
e of available hi
h speed counters on FX
2N(C)
.
Ke
:
U
- up counter input
D
- down counter input
R
- reset counter (input)
S
- start counter (input)
A
- A phase counter input
B
- B phase counter input
- Counter is backed up/latched
Input assignment:
• X6 and X7 are also hi
h speed inputs, but function onl
as start si
nals. The
cannot be
used as the counted inputs for hi
h speed counters.
• Different t
pes of counters can be used at the same time but their inputs must not
coincide. For example, if counter C247 is used, then the followin
counters and
instructions cannot be used;
C235, C236, C237, C241, C242, C244, C245, C246, C249, C251, C252, C254, I0 ,
I1 , I2 .
Counter Speeds:
• General countin
frequencies:
-Sin
le phase and bi-directional counters; up to 10 kHz.
- A/B phase counters; up to 5 kHz.
- Maximum total countin
frequenc
; 20 kHz (A/B phase counter count twice).
• Inputs X0 and X1 are equipped with special hardware that allows ver
hi
h speed
countin
as follows:
-Sin
le phase or bi-directional countin
with C235, C236 or C246; up to 60 kHz.
- Two phase countin
with C251; up to 30 kHz.
If an
hi
h speed comparison instructions (FNC’s 53, 54, 55) are used, X0 and X1 must resort
to software countin
. In this case, please see the table below:
I
N
P
U
T
1 Phase counter
user start/reset
1 Phase counter
assigned
start/reset
2 Phase counter
bi-directional
A/B Phase counter
C235
C236
C237
C238
C239
C240
C241
C242
C243
C244
C245
C246
C247
C248
C249
C250
C251
C252
C253
C254
C255
X0
U/D U/D U/D U U U A A A
X1
U/D R RDDDBBB
X2
U/D U/D U/D R R R R
X3
U/D R S R U U A A
X4
U/D U/D D D B B
X5
U/D R R R R R
X6
SSS
X7
SSS
Function
Number
Max. Combined
Signal Frequency
53 or 54 11 kHz
55 5.5 kHz
C235
