max488 problem with pic18f to PC communication

[vijin]

hi all,
I am trying to connect my PIC18f452 to the PC using MAX488. I connected exactly like in the datasheet of max488. my circuit is like that pc-MAX232-MAX488 and other side MAX488-pic. I noticed that whenever i connect one driver inputs to other side receiver, max488 getting heated. please help me to find out the problem.....

thanks

 

[betwixt]

Are you saying the MAX232 is used to convert the PC to TTL levels, then you convert TTL to RS422/485 and that connects to another MAX488 to convert it back to TTL to feed the PIC?

If so, it should work, check you have a reasonable ground between the two ends so you are no going outside the common mode range of signals and make sure the +/- differential signals are not crossed over.

Brian.

 

[vijin]

thank you brian... I checked the circuit and voltages and still the same problem..
MAX232 is giving the exact output and problem start when connecting MAX488 IC.
Can you give me schematic for max488 IC?

 

[horace1]

I avoid this problem by using USB TTL serial cables such as those from FTDI when plugged into USB they give a COM serial port that can be used by programs such as teraterm pro.

as well as 5 volt TTL they are available in 3.3 volt versions enabling one to connect directly to devices such as PIC18, PIC24, PIC32, etc