Research On Test Of Temperature Transmitter

Varieties of SITRANS TH series temperature transmitter vary their slots style and connection. During the procedure of testing, it needs to repeat testing more instruments and recording data manually, so it is inconvenient for circuit board manufacturing and daily checking. This problem could be solved by the automatic test system of temperature transmitter based on program and the hardware circuit which can simulate the temperature, and it not only improves the efficiency of the functional testing and the fault orientation gradually, but also makes it excellent generality and expansibility. This thesis combines actual project following the automatic testing requirement of large product lines on temperature transmitter to complete the automatic testing system of temperature transmitter.The system mainly uses the permutation and combination of the four lines of resistances to complete simulating the required temperature condition of testing the temperature transmitter and then completes the testing through combining the software and hardware interface circuit. First design the standard testing specification through the actual requirement and then finish designing the hardware based on the standard testing specification in order to simulate the temperature condition of the temperature transmitter. The system uses RS232to complete the communication between the computer and hardware and send the command of the computer to the hardware circuit. The electrical level chip of MAX232makes the electrical level of the RS232united with the SCM in order to make the electrical level of the RS232communicate with the SCM so that make the communication between RS232and the computer. Also complete the output of the standard voltage through the three-terminal voltage regulator of LM317and all kinds of simulations of the temperature testing through the assembly of four lines of resistances. At last transfer the electric current value of temperature transmitter to the computer using the RS232and compare the value of the electric current to the standard value through testing script for final testing of temperature transmitter to finish testing the temperature transmitter.