SECTION 6 MULTICHANNEL APPLICATIONS Walt Kester. Wes Freeman DATA ACQUISITION SYSTEM CONFIGURATIONS There are many applications for data acquisition systems in measurement and process control. All data acquisition applications involve digitizing analog signals for analysis using ADCs. In a measurement application, the ADC is followed by a digital processor which performs the required data analysis. In a process control application, the process controller generates feedback signals which typically must be converted back into analog form using a dac Although a single adc digitizing a single channel of analog data constitutes a data acquisition system, the term data acquisition generally refers to multi-channel systems. If there is feedback from the digital processor, DACs may be required to convert the digital responses into analog. This process is often referred to as data distribution Figure 6.1 shows a data acquisition/distribution process control system where ead channel has its own dedicated ADC and DAC. an alternative configuration is shown in Figure 6.2, where analog multiplexers and demultiplexers are used with a single ADC and DAC. In most cases, especially where there are many channels, this configuration provides an economical alternative DATA ACQUISITION SYSTEM USING ADC/ DAC PER CHANNEL PROCESS CONTROLLER +2 DAC ADC PROCESS DAC Figure 6.12 SECTION 6 MULTICHANNEL APPLICATIONS Walt Kester, Wes Freeman DATA ACQUISITION SYSTEM CONFIGURATIONS There are many applications for data acquisition systems in measurement and process control. All data acquisition applications involve digitizing analog signals for analysis using ADCs. In a measurement application, the ADC is followed by a digital processor which performs the required data analysis. In a process control application, the process controller generates feedback signals which typically must be converted back into analog form using a DAC. Although a single ADC digitizing a single channel of analog data constitutes a data acquisition system, the term data acquisition generally refers to multi-channel systems. If there is feedback from the digital processor, DACs may be required to convert the digital responses into analog. This process is often referred to as data distribution. Figure 6.1 shows a data acquisition/distribution process control system where each channel has its own dedicated ADC and DAC. An alternative configuration is shown in Figure 6.2, where analog multiplexers and demultiplexers are used with a single ADC and DAC. In most cases, especially where there are many channels, this configuration provides an economical alternative. DATA ACQUISITION SYSTEM USING ADC / DAC PER CHANNEL Figure 6.1