How can I measure floating analog signals?

  We recommend using a SeaI/O-570 module, which has eight 16-bit A/D inputs that are capable of measuring floating, or non-referenced, analog signals. For instructions and schematics for interfacing a SeaI/O-570 module to floating analog signals, read the Floating Signal Source Wiring Guide section of the Interfacing Analog Signals to SeaI/O-570 Modules resource article.  

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How should unused analog inputs be handled?

  Non-connected analog inputs should always be connected to the analog ground or common reference terminal. This eliminates phantom readings on all unused analog inputs. When an unused analog input is not connected to a reference voltage source, the high-impedance circuitry can react to local electrical noise causing the input to see phantom data. Connecting […]

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Should I use an RTD or thermocouple to measure temperature?

  There are several factors to consider when choosing a temperature sensor. A Resistance Temperature Detector (RTD) is typically a metal coil wrapped around a ceramic or glass core. The RTD sensor measures the electrical resistance of the metal as the temperature increases. This resistance provides an extremely accurate and repeatable measurement. An RTD sensor […]

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What is a floating analog signal?

  A floating signal source is a signal that is not connected in any fashion to the building ground system but rather has an isolated ground reference point. Examples of floating signal sources are outputs of transformers, thermistors, battery-powered devices and optically-isolated outputs.  

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What is the difference between A/D resolution and A/D accuracy?

  Resolution and accuracy are two commonly confused specifications for analog to digital conversions. Resolution defines the smallest increment of change that can be detected in an analog measurement. If you have an A/D input range of 0 to +10 volts with 12-bit resolution, then the range of 10 volts is divided into 12 bits, […]

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