Aiming at versatility and scalability requirements of multi-channel temperature acquisition

design a drawer type temperature acquisition module

through increasing or decreasing layer numbers of acquisition board

changing of number of acquisition channels can be easily implemented. This module uses FPGA as center logic controller and AD7621 for analog to digital（ A / D） conversion

analog temperature signal is converted into digital signal and transmitted to PXI chassis for display

so as to meet needs of remote real-time monitoring. Put forward using a way of querying ROM table for channel switching of analog switch

which brings great convenience to software design; for linear distortion of thermocouple caused by cold junction temperature changes

using special chip AD8495 for K type thermocouple cold junction compensation chip

ensure accuracy of measurement. The temperature acquisition module is tested to find that its acquisition precision reaches ± 1 %

which proves the practicability and effectiveness of this design.