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8 Channels, RTD Measurement

The module provides 8 measurement channels, and can be programmed for interfacing to 2, 3, and 4-wire platinum RTD sensor configurations. The 4-wire mode (default) is the most accurate, providing excellent stability and repeatability. The RTD channels feature individual A/D converters and precision excitation/current drive. Programmable lead-wire compensation is provided for inherently less accurate 2 and 3-wire configurations. All RTD channels are self-aligning because each channel is automatically "aligned" on a rotating basis to eliminate offset and gain errors throughout the operating envelope. Programmability for expected resistance range and wire modes allows for optimization of scaling/resolution, as well as flexibility in reading many RTD types.

The RT1 is used to measure temperature by providing the measured resistance of the RTD element. By correlating the characteristic resistance with the temperature algorithm of the specific RTD utilized, the temperature can be resolved. Most RTD elements consist of a length of fine coiled wire wrapped around a ceramic or glass core. The element is usually quite fragile, so it is often placed inside a sheathed probe to protect it. The RTD element is made from a pure material, typically platinum, nickel, or copper. The material has a predictable change in resistance as the temperature changes; it is this predictable change that is used to determine temperature.

Due to higher accuracy and repeatability, RTDs are increasing in use as compared with thermocouples in many industrial/embedded and test applications below 600° C.

  • Thermocouple Measurement: Interfaces with most standard NIST thermocouple types (J, K, T, E, N, B, R, and S), Self-powered, Large temperature range; up to 2300° C, Accuracy up to ±0.2° C (thermocouple type dependent), Thermo-block compensation option P/N ACC-ISO-THERM-BLK2 (If accessory used, channel 8 is automatically allocated as an RTD interface for the thermo-block compensation temperature measurement)
  • RTD Measurement: Higher accuracy and repeatability as compared with thermocouples in applications below 600 °C, Two, three or four-wire mode, Channels are calibrated at the factory for Pt100, Pt500, and Pt1000 RTDs, Single Precision Floating Point Value (IEEE-754) format, Open sensor connections are detected and reported, 1 mA, 500 µA & 250 µA excitation sources for Pt100, Pt500 & Pt1000 ranges.
  • Independently Programmable: Up to 8 RTD channels, Up to 8 Thermocouple channels.
  • Independent Mode Select: Configures Thermocouple or RTD
  • Programmable Sample Rate: Sets the sampling rate of the A/D
  • Offset Temperature: Provides ability to null for any system induced measurement errors

  • Number of Channels: 8 Channels
  • Analog Input Resolution: 24-bits per channel
  • RTD Interface: 4, 3, or 2-wire RTD interface capability. Specifically designed for use with 100Ω, 500Ω and 1000Ω RTDs, or any RTD whose maximum operating resistance is less than 4000Ω.
  • Open Line Detection: Ability to detect an open in any line or RTD in all wire modes.
  • Excitation: 100 µA per channel
  • Accuracy: ±0.1% of full-scale value @ 5 samples per second (4-wire mode only), ±0.2% of full-scale value @ 5 samples per second (3-wire mode only), ±1.2% of full-scale value @ 5 samples per second (2-wire mode only)
  • Update Rate: Each channel is updated at 5 Hz.
  • Output Format: Resistance/Temperature
  • ESD Protection: Designed to meet the testing requirements of IEC 801-2 Level 2. (4 KV transient with a peak current of 7.5 A and a Tc of approximately 60 ns.)
  • Power: 5 VDC @ 70 mA typical
  • Ground: All channel grounds are common and are isolated from system ground.
  • Weight: 1.5 oz. (42 g)
Block Diagram

(Click diagram to enlarge)

9/4/2018 8:44:31 AM
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