1771-NBSC

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.

The range of the output current is 0-25.0mA and the output resolution is 3.2µA/bit at 13 bits unipolar. The output impedance is greater than 1 megaohm. 20mA is the output drive capability into a 0-1kiloohm circuit and 25.0mA is the maximum drive capability into a 0-700ohm circuit. 140V AC RMS (continuous) is the 1771-NBSC’s output overvoltage protection rating. The output offset drifts and gain drifts are ±1.0µA/°C and ±50 ppm/°C, respectively and the calibration values are 0.5mA / 22.0mA. The Allen-Bradley 1771-NBSC should be used with the RTP-4 device. Power should be disconnected before removing or installing the module in the I/O chassis. The 1771-NBSC can perform optimally in industrial environments where the ambient temperature range is 0-60°C (32-140°F) at 5-95% relative humidity.