Interfacing RS232 / I2C

Gidday,

I'm trying to figure out if I can build a simple (read:cheap) temperature sensor by connecting an I2C compatible sensor ship (like the LM92) to an RS-232 port and get something meaningful out of it.

A circuit diagram located at http://www.eidusa.com/Electronics_Kits_RS232_To_I2C_TEMP.htm seems to indicate that this can be done without a MAX232 or other IC, but other places are selling RS232-I2C convertors for upwards of $200.

Are there any other good sources of information about such interfaces?

thanks,
Greg
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