5B47

The 5B47 is a single-channel signal conditioning module that interfaces, amplifies and filters J, K, T, E, R, S, and B-type
thermocouple. The module provides an isolated and protected precision output of 0 to + 5 V.

The 5B47 internally linearizes its input signal to provide an output that is linear with temperature. Accuracy for each type of sensor is specified in the 5B47 model table. (See Model 5B37 for non-linearized conditioning of thermocouple signals.) Accurate and System-Ready - Internal cold-junction compensation largely corrects errors arising from parasitic thermocouples formed by thermocouple connection to the input screw terminals, providing an accuracy of +0.25oC @ +25oC ambient temperature. The module 5B47 generates a predictable upscale signal to indicate an open thermocouple; for a downscale response, connect a 20M, 0.25W resistor across screw terminals 1 and 3.

The 5B47 protects the computer side from damage due to fieldside over-voltage faults. All models withstand 240V rms at their input terminals without damage, thereby shielding computerside circuitry from field-side over-voltage conditions. Further, the 5B47 is mix-and-match and hot-swappable with other 5B Series modules, so can be inserted or removed from any socket in the same backplane without disrupting system power.Inside the 5B47 Module A chopper-stabilized input amplifier provides low drift and stable gain. At the amplifier input, a stable, laser-trimmed zero-scale input voltage is subtracted from the input signal to set the zero-scale value. For user convenience, the zero of 5B47 can be optionally factory-set to meet custom needs. This allows suppression of a zero-scale input value many times larger than the total span for precise expanded-scale measurements.

Internal multi-pole low-pass filtering of 5B47 with a 4-Hz cutoff (-3 dB) provides 60 dB of normal-mode rejection (noise on signal) and enhancement of common-mode rejection (noise on signal return) at 60 Hz, enabling accurate measurement of small signals in high electrical noise.

Signal isolation by transformer coupling uses a proprietary modulation technique for linear, stable and reliable performance. The differential input circuit of 5B47 on the field side is fully floating, eliminating the need for any input grounding. A demodulator on the computer side of the signal transformer recovers the original signal, which is then filtered and buffered to provide a low-noise, low-impedance output signal. The output common of 5B47 must be kept within +3 V of power common.A series output switch eliminates the need for external multiplexing in many applications. The switch of 5B47 is turned on by an active-low enable input. If the switch is to be on at all times,the enable-input of 5B47 should be grounded to power common as it is on the 5B01 and 5B08 backplanes.