Details:

The FX2N is an old model, you can still buy their extension module and function module, the most relevant new model is FX3U.
Analog Input modules can give up to 8 simple information sources that are utilized to change over simple voltage or current signs into advanced esteems, which can be utilized by the FX PLC. 8AD analog input block converts 8 points of analog input values (voltage input, current input and temperature input) into digital values, and transfers them to the PLC main unit. You can connect this module with FX0N/FX1N/FX2N/FX2NC/FX3U/FX3UC Series PLC.

1) You can select analog inputs from the voltage input, the current input and the thermocouple input (temperature input) by the input mode setting by the TO instruction given by the PLC main unit and the connection method. At this time, a different analog input is configurable for each channel.

2)The voltage input  is selectable within the range from -10 to +10 V. The current input is selectable within the range from -20 to +20 mA and from +4 to +20 mA. The input characteristics is adjustable for each channel. The thermocouple input is selectable among the K type, J type and T type. (The input characteristics is not changable wile you using the thermocouple input.)

3) The resolution is 0.63 mV (20 V × 1/32,000) or 2.50 mV (20 V × 1/8,000) when you are using the voltage input, 2.50 µA (40 mA × 1/16,000) or 5.00 µA (40 mA × 1/8,000) when you are using the current input, and 0.1 °C when you are using the thermocouple input.

4) Up to two FX2N 8AD units are connectable to FX0N main unit, FX0N extension unit, FX1N main unit. Eight FX2N-8AD units are  connectable to the FX2N/FX3U/FX3UC*1 Series PLC. And up to four units are connectable to the FX2NC Series PLC. ( You need FX2NC-CNV-IF for connection to the FX2NC Series PLC.) ( You need FX3UC-1PS-5V or FX2NC-CNV-IF for connection to the FX3UC Series PLC, .) Data transfer with the PLC is performed to buffer memories of the FX2N-8AD by FROM/TO instructions. *1 Up to seven units are connectable to the FX3UC-32MT-LT PLC.