Appendix C Notes on Applying the I/O Modules
6F8C1575
112
(Example of selecting bleeder resistor R)
Input module DI934 (input impedance approx. 4.6 kΩ, OFF voltage 6.0 V)
Input voltage V = 24 VDC
Suppose that the switch leakage current IL = 2mA. Let R [kΩ] and P [W] be the
resistance of the bleeder resistor and the wattage, respectively. The following is
satisfied in this case:
4.6[k
Ω
]
×
R
4.6[k
Ω
]
＋
R
×
2[mA]
＜
6.0[V]
Hence,
R < 8.6 [kΩ] → R = 8.2 [kΩ]
Where
In addition you must make sure that when the bleeder resistor is selected as
above, the contact current at switch ON time is within the tolerance.
4.6 [k
Ω
]
×
R
4.6 [k
Ω
] +R
=70 [mA]
接点電流
= 24 [V]
×
(5) When you use contactless equipment such as a two-wire proximity switch, like the
case in Subsection (4) above, you must make sure that there is no danger of input
errors caused by leakage current. (For selecting the bleeder 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.
ケーブル抵抗( R)
ケーブル抵抗( R)
入力モジュール
COM
センサ
2 線式近接スイッチ
Figure C-4 Connection of contactless equipment
Contact current
Two-wire proximity switch
Sensor
Cable resistance (R)
Input module
Cable resistance (R)
To Next Page
Loading...
