1771-NBTC

The Allen-Bradley 1771-NBTC is a high-resolution I/O module in the 1771-N product range. It can work with PLC-5, PLC3, and PLC5/250 controllers. The 1771-NBTC supports 2 current outputs which are rated at 0-25 mA. It also supports 6 mV/TC (thermocouple) inputs which are rated at ±100mV and which can be used with type B, E, J, K, R, S, and T thermocouples. The 1771-NBTC draws a 1.5 A current from the chassis backplane and releases 7.5W power during operation.

For the 1771-NBTC’s input channels, the range is within ±105mV and is selectable based on the type of thermocouple used. Type B supports 300 to 1800°C, Type E supports -270 to 1000°C, Type J supports -210 to 1200°C, Type K supports -270 to 1372°C, Type R supports -50 to 1768°C, Type S supports -50 to 1768°C and Type T supports -270 to 400°C. The resolution of the input is 3.3µV/Bit (at 15 bits with sign bit). The thermocouple Types E, J, K, and T have 0.1°C resolution where Types B, R, and S have 0.3°C maximum resolution. The resolution for the display is 0.01 mV / 0.1°C. The input impedance is more than 10 megaohm. The IPTS-68 is the thermocouple linearization standard. Compensation for the cold junction is set for 0 to 70°C ±0.25°C. The value for the open thermocouple leakage current is less than 10 nA and the module needs 10s at most to detect an open input.

For output channels, the range is 0-25mA with 3.2µA/bit (at 13 bits unipolar) sensitivity. The impedance at the output is more than 1megaohm. The 1771-NBTC module can drive outputs with 20mA being the maximum for circuits having 0-1kiloohm resistance and 25.0mA being the maximum for circuits with 0-700kiloohm resistance. 140V AC RMS continuous is the rating for output overvoltage protection. The offset drift is ±1µA/°C and the gain drift is ±50 ppm/°C. It is recommended to use the 1771-NBTC with RTP-1. This module is designed for environments where the working temperature range is between 32 and 140°F at 5 to 95% non-condensing relative humidity.