Toshiba Programmable Controller PROSEC T3 - Manual (Page 59)

3. Precautions for I/O Modules
3.2
Precautions in applying
AC input modules
(1) The conditions to read the ON/OFF state of the input signal are
as follows:
Input ON time^ON delay time (OFF->ON)+input reading cycle
Input OFF time^OFF delay time (ON->OFF)+lnput reading
cycle
The input reading cycle means PLC scan cycle for the refresh
input, or the execution interval of the direct input instruction
when using a direct input instruction.
(2) When an AC output sensor is connected to the I/O module, due
to the leakage current from the sensor at OFF, there may be a
voltage which exceeds the maximum OFF voltage between the
input terminals. This will make the PLC unable to read input
OFF when the sensor is OFF. In this case, install a bleeder
resistor between the input terminals to lower the input
impedance.
For selecting a bleeder resistor, refer to 3.1 (3).
(3) if external lines for AC input become longer with using a multi­
core cable, induced current may flow to an open wire from
charged wires due to the electrostatic capacity of the cable,
causing an erroneous ON input. In this case, install a bleeder
resistor between the input terminals to lower the input
impedance. Or, you had better apply the DC input.
User's manual > Hardware
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