Mitsubishi MELSEC System Q Manual page 38

Das MELSEC System Q
For the MELSEC System Q input modules for DC voltages are available for negative common
or for positive common connections. For some modules like the QX71 you can choose
between these two connection methods.
Negative common connection
A sensor connected to a negative common input module connects the positive pole of an exter-
nal power supply with a PLC input. The negative pole of the power supply is connected to the
common terminal for all inputs of this group. When the sensor is actuated, the input signal cur-
rent flows into the input.
Positive common connection
A sensor connected to a positive common input module connects the negative pole of the
external power supply with a PLC input. The common terminal for all inputs of this group is
connected to the positive pole of the power supply. When the sensor is actuated, the input sig-
nal current flows out of the input.
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Input module
I
Input
I
Input
24 V DC
Input module
24 V DC
I
Input
I
Input
Digital Input and Output Modules
MITSUBISHI ELECTRIC