5: S
PECIAL
F
UNCTIONS
5-40
FC5A M
ICRO
S
MART
U
SER
’
S
M
ANUAL
FC9Y-B1268
Key Matrix Circuit
The key matrix structure includes sequentially-numbered input points along the top and sequentially-numbered output
points along the side. The I/O connecting blocks include a diode and a switch. The following diagram illustrates an exam-
ple of key matrix circuit consisting of 5 inputs and 3 outputs.
SW06
SW01
SW11
SW12
SW08
SW09
SW14
SW10
SW15
SW07
SW13
SW02
SW03
SW04
SW05
Output
Q0
Q1
Q2
Transistor
Sink Output
Input
I0
I1
I2
I3
I4
DC Input
Output
Q0
Q1
Q2
Note:
For the circuit above, a transistor sink output module must be used. When using a
transistor source output module, reverse the direction of diodes.
Diode rating is:
Average rectified current
100 mA
Reverse voltage
100V DC
Internal Relay Allocation
The example of a key matrix configuration shown on page 5-39 stores input information to 15 internal relays starting with
internal relay M0. The switches are assigned to internal relays as shown below:
Outputs
Inputs
I0
I1
I2
I3
I4
Q0
M0
(SW01)
M1
(SW02)
M2
(SW03)
M3
(SW04)
M4
(SW05)
Q1
M5
(SW06)
M6
(SW07)
M7
(SW08)
M10
(SW09)
M11
(SW10)
Q2
M12
(SW11)
M13
(SW12)
M14
(SW13)
M15
(SW14)
M16
(SW15)
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