Programming S7-300 to read RTD.

I am using the Siemens S7-300 analog input AI8x12bit SM331 to read temperature from a two wire platnium RTD (100ohm). I am pretty sure that I have connected the RTD correctly and configured the card properly. I am now wondering if the programming i am using could be wrong. If anyone has any suggestions as to what I need to use in the line of ladder logic programming to get this to work please let me know.

Hello Brian;
There is no particular programming techniques to read values from the analog inputs ion Siemens' world. Once correctly configured and parametrized, you should be able to get some reading in the addresses selected for the input channel.
You can monitor the values in your input register directly in HardwareConfig (right-click the SM331 in the rack, click on Monitor/force); you can monitor the same register in the program blocks, everytime you use that address (for a MOVE or Compare instruction, for example); you can also use a VAT table, specifying address PIWxxx.
Here is a look at the values you should be recieving from the PT100. Even if the module is not wired properly, you should be reading (hex)7FFF or (hex)8000 in your input registers (overflow and underflow values.
It would be great if, when you request further help, you could be more specific on the details of your configuration and programming. Screenshots are also useful.
Hope this helps,
Daniel Chartier

is this a pt100 input card that means is it suitable for three or four wire pt100 din style?
two wire is not very much used by the way. as it is not precise.
buy a converter to read this temp and convert it to a 4/20 ma signal that is cheapest way.
and where is the source coming from there should be a power source of 1 mA to the sensor.
maybe a small bridge inside the unit.

Hello shooter;
this particular analog input module can be configured to read currenty, voltage, TC and RTD signals, in various ranges (and each 2 input channel can be configured differently). When configured for RTD (PTx00) it can be connected as 4-wire, 3-wire or 2-wire (using different connection schemes suggested by Siemens). I agree that 2-wire RTD connections are not as precise or noise-immune, but they do work with this module.
Hope this answers your point,
Daniel Chartier

For a 2 wire RTD- it still has to be jumpered at the module. Is this done??
Also has the jumpers (square plug) on the side of the module set?
Is it set properly in the hardware config.??

i am connected pt100 RTD to my plc through transmitter(modbus) output is 4-20ma...how can i program for it...plc is kinco cpu508..my plc no analog module