7B40 Isolated, Voltage or Current Input

The 7B40 is a single-channel signal conditioning module that interfaces, amplifies and filters unipolar and bipolar millivolt and voltage inputs and provides a protected precision output of either +1 V to +5 V or 0 V to +10 V. Model 7B40 features a nonlinearity of ±0.02% maximum and an accuracy of ±0.1% maximum (±0.01% typical). To accurately measure low level signals in electrically noisy environments, 1500 V rms of galvanic transformer-based isolation with a common mode rejection (CMR) of 110 dB @ 50/60 Hz and a normal mode rejection (NMR) of 100 dB @ 50/60 Hz are provided. Rated to operate with a nominal +24 V DC supply, Model 7B40 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.

Inside the 7B40 Series Module

The floating differential input of Model 7B40 is fully protected up to 240 V rms line voltage. A one-pole 10 KHz filter preconditions the input signal prior to amplification by a low drift input amplifier. Amplitude modulation is used to implement transformer isolation (1500 V rms input-to-output and power). Isolated front-end circuitry power is supplied by a DC/DC converter. The output section contains a four-pole low pass filter (-3 dB @ 10KHz), a buffer amplifier and a power oscillator. The four-pole output filter and subsequent buffer ensures that a low noise, low impedance (<1Ω ) signal is available at the output to drive loads of 2 kΩ minimum.