Research Of The Performance Testing System For The Train Axle Temperature Annunciator

Temperature Annunciator is one of the most important apparatus to insurethe safety of train,its performance has something to do with the safety of traingreatly.After researching the principle of the Temperature Annunciator , in orderto satisfy the need of each train hostler,According to the National RailwayDepartment's criterion,excogitated a new system to test the performance ofTemperature Annunciator.This system is made up of the computer control andtest technology.Meanwhile,this system is also a system that is maintainedeasily,used simply,and works steadily.The apparatus can identify the digital temperature sensor and the analogtemperature sensor,this facilitate the design of the circuit which supply thevoltage to the Temperature Annunciator.We just need to supply voltage by theformula following. V =1235mV ? 4.36×T(±4.36mV)to the Temperature Annunciator,and then can simulate the temperature to test theTemperature Annunciator needed.In this system,it implement the continuousadjustment of temperature by D/A transformer.In this unit,the crucial problem isthe noise effect.In order to solve this problem we design the stelliform systembus to carry the voltage.When it comes to testing the constant current of temperature annunciator,theprecision is the most important thing should be considered.The constantcurrent(300μA) outputted by the temperature annunciator just present 200mSduring the temperature sampling.So,the test circuit must lock this short period totest the constant current.In this system,we design a track circuit to distinguish theperiod when the constant current appear.Additionally,in order to insure theprecision of test,we use the precise resistance and 12bit A/Dtransformer(A/D574).This system is a test&control system based on the RS232 serialcommunication.In serial communication,we should pay attention to the stabilityof system and the validity of data.In this system we used the CRC to validate thedata sent through serial port.In addition,we proposed a new method to reckon theCRC Code.In this method,we just need to reckon the CRC Code of each datafrom 0 to 255 beforehand,and store these CRC Code as a table in PC orMCU;When we want to reckon the CRC Code of several bytes,we just need tolook for CRC Code of each byte ,in the table stored before,and do different addalgorithm.We use Delphi to make the application program.In Delphi,We installed theactivex control component(MSCOMM)of VB,and then,we can enable PC and...