1771-NIS

The Allen-Bradley 1771-NIS is an I/O module which belongs to the 1771-N high resolution I/O module series. It is equipped with 8 current input channels rated for 4-20mA. The 1771-NIS module provides power for the input circuit loops. The current drawn by the 1771-NIS from the I/O chassis backplane is 2.4A and the total power dissipated is 12W. The 1771-NIS interfaces with PLC-5/250, PLC-3 and PLC-5 controllers.

The current range supported by the 1771-NIS’s input channels is 0.1 – 21mA. The resolution for the input channels is 330nA/bit (at 16 bits unipolar) with the impedance at the input being a maximum of 300ohm. The module-supplied loop power is 20 – 30V DC (0 to 20mA range). The 1771-NIS module needs a maximum of 5s to detect an open input circuit and it provides 24V DC overvoltage protection. A range of 50 dB to 60 dB provides the values for normal mode rejection whereas the typical common mode rejection is 150 dB. The value for the offset drift is ±200nA/°C whereas the value for the gain drift is ±95 ppm/°C. The update time per module is a maximum of 25s and the bandwidth range at input channels is 9 Hz. The under-range and over-range limit values are 3.2mA and 21mA, respectively. The values for the 1771-NIS’s input channel calibration are 1 mA / 21 mA.

Allen-Bradley recommends using the 1771-NIS in combination with the RTP-4 (which is suitable for applications other than those where thermocouples are required). The power to the I/O chassis should be turned off before installing or removing any I/O module. The optimal working temperature range for the 1771-NIS is 0 to 60°C at 5 to 95% relative humidity (non-condensing).