7B14

The 7B14 is a low cost, single-channel signal conditioning module that interfaces, amplifies and filters input voltages from a wide  variety of two-and three-wire platinum, copper and nickel Resistor Temperature Detectors (RTDs) and provides a precision output of either +1 V to +5 V or 0 V to +10 V, linear with temperature. Model 7B14 features a nonlinearity of +0.05% maximum (Pt and Cu RTDs). RTD excitation current, three-wire lead resistance compensation and a predictable upscale open circuit indication provide a complete signal conditioning solution. Rated to operate with a nominal +24 VDC supply, Model 7B14 is mix-and-match and hot-swappable with other 7B Series input modules, so it can be inserted or removed from any socket in the same backplane without disturbing system power.

The three input pins of Model 7B14 are fully protected up to +30 VDC. A 250 uA excitation current for platinum and nickel RTDs and a 1mA excitation current for copper RTDs is provided to create an input voltage to the 7B14. This current also provides the upscale open circuit indication. A one-pole 3 Hz filter preconditions the RTD signal prior to amplification, provided by a low drift input amplifier. The output section contains a two-pole low pass filter (-3 dB @ 3 Hz) and a buffer amplifier. The two-pole output filter and subsequent buffer ensure that a low noise, low impedance (<1Ω) signal is available at the output to drive loads to 2 kΩ minimum.