Regular and even cheap J or K type thermocouple will do fine. ICP A/D converters (I-7018) and any controller model handling RS485, offered by Tri will do the rest. Code examples for the converters are available on the web site and controller manuals. The rest is simple Basic. Logging to a PC may require some more esoteric Java, C++ or VB knowledge. If you just need to measure and nothing to control, an I-7018 plus Auto 485 is all you need to send the values to a PC through any RS232 port there. Premises for what you need on the computer are the same, just some changes on what comes and goes to the A/D, very well described in the manual.
Thermocouples may become expensive if you have long runs between measuring point and the A/D. If so, I would suggest some component type PT100 (KTY81 from Phillips) or other temperature sensor like LM35 or LM335 from National plus some electronics described in their application notes. LM35 is perhaps the best choice to build a 2 wire sensor with little additional components, needing no calibration and giving a 10 mV per degree C output. The I-7018 will be a good choice for same and may read up to 8 of these sensors.
