i am looking for 3 circuits with connection diagram
1) which convert ttl input in to rs232 output
2) which convert ttl input to rs 485 output
3) which covert r232 to rs 485 output
i know we can do with max 232 and max 485 IC . But how to make it working.how ttl inputs are given and output has taken
As posted by CrossRoads, it's each to convert from TTL serial comm to and from RS-232 comm OR to and from RS-485 devices by using an appropriate converter chip. But what is not clear is your statement to want both? On the same single AVR serial port at the same time?
What is connecting to these two interface levels? Is your intention to be able to communicate to two external devices, one at RS-232 and one at RS-485 at the same time? While it's not hard to have the arduino send characters out to two devices at different voltage levels at the same time from one serial port, there would be problem in how two different devices can respond back to a single AVR Rx pin as there would be nothing to prevent the two senders from stepping on each other. Some kind of electrical ORing connection would be needed as well as a software serial protocol to prevent two external devices sending at the same time.
So maybe a little clearer description of what you are trying to accomplish would be in order?