Mitsubishi Electric MELSEC-Q Series - Page 107

3 REPLACEMENT OF I/O MODULE
3 - 54
(39)Specifications comparison between A1SX81 (24VDC, negative common) and QX81-S2
: Compatible, : Partially changed, : Incompatible
*1 Check the specifications of the sensor or switches to be connected to the QX81-S2.
*2 The following shows the derating chart.
Specifications A1SX81 QX81-S2
Compat-
ibility
Precautions for replacement
Number of input points 32 points 32 points 
Isolation method Photocoupler Photocoupler 
Rated input voltage 12/24VDC 24VDC 
Rated input current Approx. 3mA/Approx. 7mA Approx. 6mA
The rated input current is
reduced.
*1
Operating voltage range
10.2 to 26.4VDC
(ripple ratio within 5%)
20.4 to 28.8VDC
(ripple ratio within 5%)

Maximum number of
simultaneous input points
Refer to the derating chart.
*2
Refer to the derating chart.
*2
Use it within the range shown in
the derating chart.
On voltage/on current 8VDC or more/2mA or more 15VDC or more/3mA or more
The on voltage/on current differ.
*1
Off voltage/off current 4VDC or less/1mA or less 5VDC or less/1.7mA or less
The off voltage/off current differ.
*1
Input resistance Approx. 3.3k Approx. 3.6k
The input resistance is
increased.
*1
Response
time
Off  on
10ms or less
(24VDC)
1ms/5ms/10ms/20ms/70ms or less
(Configure
the setting in the PLC
parameter dialog box.
)
10ms is set by default.

Set the input response time of
parameter to the default value
(10ms).
On  off
10ms or less
(24VDC)
1ms/5ms/10ms/20ms/70ms or less
(Configure
the setting in the PLC
parameter dialog box.
)
10ms is set by default.

Common terminal
arrangement
32 points/common
(common terminal: 17, 18, 36)
32 points/common
(common terminal: 17, 18, 36)

Operation indication On indication (LED) On indication (LED) 
External connection
system
37-pin D-sub connector
(accessory)
37-pin D-sub connector
(sold separately)

Existing external wiring can be
used.
Note that the connecting
direction of the connector is
inverted.
Applicable wire size
0.3mm
2
0.3mm
2
(A6CON1E)

Current consumption 0.08A (typ. all points on) 0.075A (typ. all points on) 
External dimensions 130(H)34.5(W)93.6(D)mm 98(H)27.4(W)90(D)mm
Weight 0.24kg 0.16kg
(A1SX81) (QX81-S2)
26.4VAC
On ratio (%)
On
ratio
Ambient temperature
100
90
80
70
60
50
40
010 20 30 40 5055
30
20
(%)
10
(31.25%) 24VDC
(18.75%) 28.8VDC