Dataforth Corporation of Tucson, Arizona, announces the availability of the newest additions to its family of SensorLex® 8B isolated analog signal conditioners: the 8B34 linearized 2- or 3-wire RTD (Resistive Temperature Device) input modules, the 8B35 linearized 4-wire RTD input modules, and the 8B36 potentiometer input modules. All have 3Hz signal bandwidth.

Both the 8B34 and 8B35 input modules isolate, filter, amplify, and linearize a single channel of temperature input from an RTD and provide an analog voltage output. These modules interface to 100? platinum RTDs and minimize measurement errors.

The 8B36 input modules isolate, filter, and amplify a single channel of potentiometer input and provide an analog voltage output. They interface to potentiometers up to 10,000? and have ±0.05% measurement accuracy and ±0.02% linearity.

Specific applications for the new modules include the following:

8B34: Any process, industrial or other, which requires precise measurement of temperature. RTDs are used instead of thermocouples when the most stable and accurate measurements are required. 8B34 modules have a low drift over time and temperature and do not add significant measurement error.

8B35: Like the 8B34, this family of modules is used to measure temperature, but designed for applications requiring ultimate precision. 8B35 modules use a 4-wire measurement technique that almost completely eliminates measurement errors due to leadwire resistance. These modules are used when leadwires are extremely long or are different wire gauges.

8B36: Interfaces to potentiometers and slidewires using a 2- or 3-wire connection. Sensors with this format include tension transducers, level indicators, rotary or linear position transducers, accelerometers, and pressure transducers.

Excitation for the RTD in the 8B34 modules and for the potentiometer in the 8B36 modules is provided from the module using two matched current sources. When using a 3-wire connection, this method allows equal currents to flow through the sensor leads, canceling the effects of lead resistances. In the 8B35 modules, RTD excitation is provided from the module using a single precision current source.

Since the excitation current does not flow in the 8B35's input signal leads, RTD measurements can be made independent of lead resistance. In all three of these module series, excitation currents are small (0.25mA in the 8B34 and 8B35, and equal to or less than 0.25mA in the 8B36); this minimizes self-heating of the sensor, which can be a source of measurement error.

Signal filtering in the 8B34, 8B35, and 8B36 is accomplished with a three-pole filter optimized for time and frequency response that provides 70dB of normal-mode rejection at 60Hz. One pole of the filter is on the field side of the isolation barrier for anti-aliasing; the other two are on the system side.

The three new modules provide 120dB common-mode rejection and, like all modules in Dataforth's 8B family, also feature the following specifications:

• 1500Vrms Transformer Isolation
• ANSI/IEEE C37.90.1 Transient Protection
• Input Protection to 240VAC Continuous
• Low Drift with Ambient Temperature
• -40°C to +85°C Operating Temperature Range
• 5V Power
• UL and CE Certifications Pending
• Mix and Match Module Types on Backpanel

Developed in response to customer requests worldwide for smaller, lower cost isolated signal conditioners, the SensorLex® 8B family ensures fully functional Instrument Class® performance in a package only one-fifth the size of competing modular products. Since its introduction, the 8B line has grown to include 17 family groups with a total of 106 modules that interface to a wide variety of analog signals such as volt, millivolt, current, temperature (thermocouple and RTD), position, frequency, and strain measuring devices.

Measuring only 1.11 x 1.65 x 0.4 inches (28.1 x 41.9 x 10.2mm), the 8B signal conditioner is 80% smaller than similar products, making it ideal for embedded or portable applications such as mobile test stands, COTS military and defense applications, miniaturized security and surveillance systems, and embedded process controls for semiconductor manufacturing equipment. With the SensorLex® 8B, it is now possible to incorporate high-performance modular I/O on a per-channel basis for any embedded monitoring or measurement and control system; because the 8B provides an Instrument Class® analog output, interfacing to almost any PC/104, compact PCI, VMEbus, PXI, or proprietary data acquisition system board is very easy.

Housed in a solid, potted thermoplastic plug-in-the-panel package with flammability rating of UL-94 V-0, the 8B family of isolated signal conditioners is specifically designed to protect user equipment, while reducing electrical noise and enabling convenient system expansion and repair.

Operation and storage temperature for the 8B models is -40°C to +85°C; relative humidity range is zero to 95% noncondensing. All models meet the requirements of EN61000-6-4 (radiated/conducted emissions) and EN61000-6-2 (ESD/RF/EFT immunity). For operation in hazardous environments, North American Class I, Division 2, and European Group II, Category 3, approvals are pending.

Design-in accessories for the 8B line include a selection of backpanels (2, 4, 8, and 16 channels) that provide screw-terminal inputs and outputs as well as a DB25 header connector. A power supply module in the same 8B form-factor is offered to accommodate input voltages of 12 to 28VDC and provide 5VDC output at 2A to power any combination of 8B signal conditioners. The 8BPWR-2 module plugs into its own socket on the backpanel, which protects the power supply module from transients and reverse wiring errors.

Coming months will see the introduction of strain gage input modules, 2-wire transmitter interface modules, and frequency input modules. Custom signal conditioning models are available to meet unique signal conditioning needs, and the 8B line will soon be available in a DIN mount configuration.

For additional information and pricing, call 800-444-7644 toll-free, or e-mail at sales@dataforth.com.

Original release: August 31, 2005