Toshiba Vm Series Instruction Manual page 142

resistor, see Subsection (4) above.)
In addition, although the switch is ON, the input terminal voltage may not
reach the ON voltage, thereby disabling input ON to be read. This is due to
influence of the saturation, or residual, voltage. Pay particular attention if
the input voltage is low or the input wiring is long.
Two-wire proximity switch
Sensor
Figure.C.1-4
Let R [Ω] be the cable resistance. Let Vd [V] be the proximity switch's residual
voltage. Let Zi [Ω] be the input module's proximity input impedance. In this case,
the following expresses the voltage Vi [V] that is applied between the input terminals
of the input module when the proximity switch is turned on:
If Vi above decreases below the minimum ON voltage of the input module, you need
to increase the input voltage or make provisions that decrease the cable resistance
R.
(6) If the input filter time constant is small in an input module such as DI934,
influence of contact chattering may cause erroneous input data to be read.
If a quick response is required, make connection with contactless equipment
and also take the noise into sufficient consideration.
(7) If a long input cable is routed, you also need to take the noise into
consideration in addition to the voltage drop that is due to the cable's
conductor resistance. Note the following items:

Wire the cable at the minimum distance without making unnecessary
loops.

Separate the cable from any power line or high-frequency signal line as
far as possible. Keep it away 200 mm or more from them, or shield it
with iron plate.

If possible, relay the cable at the inlet to the control board.

Consider using a shielded cable or twisted pair cable in some cases.

Install the bleeder resistor to lower the input impedance.
Cable resistance (R)
Cable resistance (R)
Connection of contactless equipment
V-Vd
Vi = Zi
2R + Zi
Unified Controller Vm Series Controller typeS Instruction Manual
Input module
COM
V
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