Care while interfacing ?

[truebs]

Hi,
I am trying to interface self made circuit to my PC using serial port.
As it's my own PC and its just my 2nd project ,so i want to be on safe side.
Please tell me the care to be taken while interfacing so that i may not damage my system.
Also suggest some preventive measures i can take ?

With a Thanks in mind !
Truebs.

 

[Cortex]

are you using a Max232 between ur project and the pc ??

 

[pisoiu]

Even if it is not recomended, mixing or shorting wires in the RS232 will not cause permanent damage, in most of the cases. I think you should be carefull especially if your device is powered from a switching mode power supply. If your power supply and/or PC's power supply is accidentaly disconected from earth, high voltages may occur between the ground of your device and the PC ground. When you plug the connection into the serial port you may burn something. Before plugging, check the AC voltage between those two grounds. It should be near 0.

/pisoiu

 

[truebs]

hi yes i am using max232 .
and for secondly m not using smps for power supply ,i am using a seperate dc battery instead.

Please tell me how can i be sure of voltages and current limits.


thanks !!!

 

[Cortex]

use zener Diodes to protect the input of the Max232 and your pc port

Don't Forget to check the GND before testing anything

 

[LuCaCoS]

You can also use electolit capacitor. 4 same electolit capacitors: connect your dc battery to max232 trough the capacitor and do the same for the gnd, the other two capacitors place them in their position on max232.

I have project where i use max232 and that is the way usually secure the chip.
That's my opinion.

 

[vdaniel]

The main reason of possible damage are different common mode voltages. It usualy happens when powered devices are connecting, but not in your case, because with the battery powered second side you are absolutely safe.

Varuzhan