ICOM 200 User Manual

Page of 55
ICOM-manual 
Opto inputs 
The ICOM-241 has eight optocoupler inputs suited for an input voltage range 
of 5...12 VDC. To use higher input voltages, as 24V for example, an additional 
serial resistor in the input line is used. The resistor value is selected in 
accordance to 4...50mA input current needed for the logical “1” level. 
The internal resistance is 680 Ohm / 0,25 W. If now another input voltage is 
needed, the totally required resistance can be calculated with the following 
formula: 
R
ges
 = (U
E
-1,3V)/I
U
E
 =  Input voltage 
 
I
D
 = 
Current into the optocoupler 
 
R
ges
 =  Total resistance
 
Example: 
Is e.g. an input voltage of 24 V with a current of 10 mA wanted, you get from 
the above formula Rges = 2270 Ohm. This means either the internal 680 Ohm 
resistor has be replaced with a 2200 Ohm resistor (rounded to norm value), or 
a resistor of 1590 Ohm has to be connected in series.  
Attention: 
When calculating the protective resistance the maximum dissipation of the 
resistor has to be considered! 
 
Tiny-Tiger
®
 Port 
Optokoppler 
DB-25 socket 
P80 Opto 
In0 
P81 Opto 
In1 
14 
P82 Opto 
In2 
P83 Opto 
In3 
15 
- Opto 
GND 
 
The following program reads the status of the optocoupler inputs into a 
variable and sends it out through serial port 0. 
3-4 
Wilke Technology GmbH • 0241 / 918 900 • http://www.wilke.de/ • support@wilke.de