Data Acquisition I/O Modules

Data acquisition I/O modules or cards have both input and output functionality. Digital or discrete I/O modules include on-off signals used in communication, user interface, or control.  Data acquisition is the processing of multiple electrical or electronic inputs from devices such as sensors, timers, relays, and solid-state circuits for the purpose of monitoring, analyzing and/or controlling systems and processes. Device performance, analog outputs, form factor, computer bus, connection to host, and environmental parameters are all important specifications to consider when searching for data acquisition I/O modules.

Digital I/O channels, differential analog input channels and resolution are all important device performance parameters to consider when specifying data acquisition I/O modules.  Digital I/O channels are digital or discrete channels are used for low-level on-off signals used in applications such as communication, user interface, or control.  Differential channels use the difference between two signals as an input; common mode is filtered out. In some systems, differential inputs are combinations of two single-ended inputs; in this case, twice the number of differential channels would be available as single-ended inputs.  Resolution refers to the degree of fineness of the digital word representing the analog value for I/O modules. A ten-bit number contains 2¹⁰, or 1024, increments. A 0-10V signal could therefore be resolved into approximately 0.01V increments. A 12-bit representation would be in 2¹² (4096) increments, or divisions of 0.0024V for the same signal. Each additional bit doubles the resolution, and one bit is required for the polarity (sign) of a number.  Choices for analog output include voltage output, current output, and other specialized outputs.  The form factor of data acquisition I/O modules can be IC or board mount, circuit board, panel or chassis mount, modular bay or slot system, rack mount, DIN rail, and stand-alone.

Choices for computer bus for data acquisition I/O modules include CompactPCI, IBM Microchannel, IEEE 1394, ISA or EISA, Mac PCI (Nubus), MIX bus, Multibus (I and II), PC/104 (PC/104-Plus, EBX), PCI, PCMCIA (PC Card), PXI Bus, PMC Bus, STD Bus, SUN Sbus, USB, VME Bus, and VXI or MXI Bus.  Connections to the host that are available for data acquisition I/O modules include direct backplane interface, RS232, RS422, RS485, USB, IEEE 1394, GPIB (IEEE 488, HPIB), SCSI, TTL, parallel interface, Ethernet, modem, and radio or telemetry.  An important environmental parameter to consider when searching for I/O modules, data acquisition, is the operating temperature.

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Part Numbers for Data Acquisition IO Modules