Design and implementation of analog acquisition card based on new communication method

For different analog-signals,special acquisition modules are expanded in PLC control system.If current multi-signal-types analog acquisition module is used,PLC serial port(485/232) and communication protocol such as MODBUS are needed.The both methods are complex and of poor price performance ratio.In order to slove the problem,a multi-functional analog acquisition card was developed,in which only two PLC digital input-ports instead of PLC communication interface were used.The results indicate that the card can real-timely acquire temperature,standard current and voltage,also can communicate with any type PLC and meet corresponding requirements of EFT testament.This design is universal and has high price performance ratio.The card has been used in PLC control system reliably.