johnyp,

Just by looking at the datasheet I don't think that you can connect this ds18b20 directly to a max232, if that is what you are trying to do. You need to initialize your ds18b20 and then send ROM commands and funtion commands to it from your MCU.

Connect the ds18b20 to any port in your MCU and connect your MCU to a max232. Read the datasheets. The answer is in there.

http://datasheets.maxim-ic.com/en/ds/DS18B20.pdf

http://datasheets.maxim-ic.com/en/ds/MAX220-MAX249.pdf

Robert