5: S
PECIAL
F
UNCTIONS
FC5A M
ICRO
S
MART
U
SER
’
S
M
ANUAL
FC9Y-B1268
5-41
Maximum Input Read Time
The maximum period of time required to read input signals in the key matrix circuit is called the maximum input read
time, which can be calculated using the following formula. When the input ON duration is shorter than the maximum
input read time, the input may not be read.
Maximum Input Read Time
Output Points
I/O Delay Time
Scan Time
--------------------------------------
1
+
1
+
Scan Time
=
The scan time can be confirmed using special data register D8023 (scan time current value in ms).
The I/O delay time depends on the modules used for inputs of the key matrix. The I/O delay time for CPU modules and
I/O modules are listed in the table below.
The value of [X] in the above formula represents the maximum integer value less than or equal to X. For example, [0.23] represents 0,
and [2.5] represents 2.
Module Used for Key Matrix Inputs
CPU Module
I/O Module
FC5A-C24R2
FC5A-C24R2C
FC5A-D16RK1
FC5A-D16RS1
FC5A-D32K3
FC5A-D32S3
FC5A-D12K1E
FC5A-D12S1E
FC4A-N08B1
FC4A-N16B1
FC4A-N16B3
FC4A-N32B3
FC4A-M08BR1
FC4A-M24BR2
I/O Delay Time
Approx. 5 ms + Input filter value (Note 1)
Approx. 10 ms (Note 2)
Note 1:
The input filter can be selected using WindLDR. From the WindLDR menu bar, select
Configuration
>
Input Configuration
>
Input Filters
. Different input filter values can be selected for inputs I0 through I7 in four groups. When the inputs used for the key
matrix contain different input filter values, the largest input filter value takes effect for the I/O delay time.
Note 2:
When using expansion interface modules (FC5A-EXM2 or FC5A-EXM1M and FC5A-EXM1S) for key matrix inputs or outputs, the
I/O delay time is approximately 22 ms.
Example: Calculating Maximum Input Read Time
This example calculates the maximum input read time for a key matrix consisting of 4 inputs and 16 outputs to read 64
points of input signals.
Conditions
MicroSmart System Setup
FC5A- FC4A-T16K3
Function
Area
Settings
Key Matrix Input
I4 to I7 (4 inputs)
Key Matrix Output
Q30 to Q47 (16 outputs)
Input Filter (Group 4)
3 ms
Scan Time
10 ms (D8023 value)
I/O Delay Time
5 ms + Input filter value (3 ms) = 8 ms
Calculation Formula
Output Points
I/O Delay Time
Scan Time
--------------------------------------
1
+
1
+
Scan Time
16
8 ms
10 ms
--------------
1
+
1
+
10 ms
=
16
1.8
1
+
10 ms
=
16
1
1
+
10 ms
=
Maximum Input Read Time
320 ms
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