ANALOG INTERFACE DEVICE FOR MULTIPLE-INPUT INFORMAANALOG INTERFACE DEVICE FOR MULTIPLE-INPUT INFORMATION AND MEASURING SYSTEM TION AND MEASURING SYSTEM

摘要

The proposed analog interface device for multiple-input information and measuring system is designed for entering current signals from the process parameter transducers into a personal computer. The interface device contains current-to-voltage transducers, a multiplexer, a microprocessor, an analog-to-digital converter, a power-supply unit, and an output optoelectronic coupler for isolating electric circuits. The inputs of the current-to-voltage transducers are connected to the outputs of the corresponding transducers, and the outputs are connected to the corresponding inputs of the multiplexer. The output of the multiplexer is connected to the input of the analog-to-digital converter. The output of the analog-to-digital converter is connected to the input of the microprocessor. The control inputs of the multiplexer and the analog-to-digital converter are connected to the output of the microprocessor. The power-supply unit is isolated from the interface device circuit. Each current-to-voltage transducer is designed as a differential amplifier with symmetrical current inputs. The proposed invention provides high accuracy and noise immunity in transmitting signals from process parameter transducers.