The Allen-Bradley 1771-NBSC is an I/O module that is part of the Allen-Bradley 1771-N series of output modules. It has six 4-20mA current inputs and two 0-25mA current outputs. The maximum current drawn by the 1771-NBSC I/O module from the chassis backplane is 2.6A and the amount of power it dissipates during operation is 13W. It can be used with the Allen-Bradley PLC-3, PLC-5, and the PLC-5/250 programmable controllers.
For the inputs, the range of the current is 0.1 – 21 mA and the input resolution is 330nA/bit at 16 bits unipolar. The input impedance reaches a maximum of 300ohm. The power supplied by the 1771-NBSC module for the current loop is 20 – 30V DC (0-20mA). The module provides an input overvoltage protection rated at 24V DC continuous. The 1771-NBSC module requires 5s to detect open inputs. It offers a 50/60 dB minimum normal mode rejection and the typical common mode rejection is 150 dB. The offset drift and the gain drift are ±200nA/°C and ±95 ppm/°C respectively. The 1771-NBSC’s range of input bandwidth is 9Hz and the calibration values are 1.000mA/21.000mA. The under range and over range thresholds are 3.2mA and 21mA respectively.
