Toshiba SX 2000 - Manual (Page 128)

Chapt.3 Precautions for
I/O Modules
3
3.1 Precautions for DC Input Modules
(1) Read conditions for the ON/OFF changes of the input signals are :
Input ON time ^ time (OFF^ON)+lnput reading cycle
Input OFF time > OFF delay time (ON^OFF)+lnput reading time
The "input reading cycle" means the S2T scan cycle for the refresh input, or the
execution interval of a direct input instruction when the instruction is used.
(2) For some external contacts, the input current (8mA/24V for DI633; 4mA/24V for
DI634/635) of modules may not be able to maintain contact reliability. In the
case, install a bleeder resistor between the input and common terminals to
increase the contact current.
Contact Input module
i
R=-
l-h
Wattage P=--------x (2.5-3)
R
(An example of selecting a bleeder resistor R)
Input Voltage V= 24Vdc
Input module DI633(8mA/24Vdc)
When the contact requires 50mA current;
Resistance value R of a bleeder resistor R =
24fVl
50[mAl - 8[mAl
= O.efKQl
Wattage P of the bleeder resistor p = x (2.5 -3)=3fWl
(560n)
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