The 1771-IL is an isolated analog input module by Allen-Bradley and Rockwell Automation. It has 8 fully isolated differential inputs per module and a 16-bit resolution that is binary over full range. Typical voltage accuracy is 0.01% of full scale range at 25 degrees Celsius while maximum voltage accuracy is 0.05% of full scale range at 25 degrees Celsius. Typical current accuracy is 0.06% of full scale range at 25 degrees Celsius while maximum current accuracy is 0.1% of full scale range at 25 degrees Celsius. Both the linearity and repeatability for the 1771-IL are ±1 LSB. This module has an isolation voltage of ±1000 Volts peak, channel to channel, channel to ground for 1 second. The voltage mode for input overvoltage protection is 140 Volts AC (rms) continuous while current mode is 8 Volts DC continuous.

The 1771-IL has an input impedance of >10 megohms for voltage ranges and 250 ohms for current ranges. Common mode rejection is >120 decibels at 60 Hertz and 1K ohm source imbalance. Common mode impedance is >50 megohms shunted by ˂5 nF. Normal mode rejection is >120 decibels at 60 Hertz. The 1771-IL has a 10 seconds (maximum) time to detect open circuit and a power dissipation of 6.5 Watts (maximum). Thermal dissipation for the module is 22.2 British Thermal Units (BTU) per hour (maximum). It has an internal scan rate of 50 milliseconds for 8 channels. Environmental specifications for the 1771-IL include an operational temperature of 0 to 60 degrees Celsius and a storage temperature of -40 to 85 degrees Celsius; relative humidity is 5% to 95% for operating and 5% to 80% for non-operating.

When it receives an analog input signal, the Allen Bradley 1771-IL transforms the signal from 0000 to +409510 for unipolar input ranges, which included 0 to 5 volts, +1 to +5 volts, 0 to +20 milliamperes, and +4 to +20 milliamperes. Additionally, for bipolar input ranges, this device changes the signal from -409510 to 409510, which include +5 volts, +10 volts, and +20 milliamperes. The term "unipolar" refers to a value at which the count starts at zero. A bipolar value is one where the largest positive number has a negative complement. A unipolar number has no sign, but a bipolar number does. This module has a 16-bit binary resolution with full-range resolution. It has eight (8) fully isolated differential inputs per module. At 25 degrees Celsius, the voltage accuracy of this device is 0.05 percent of the full-scale range. For input overvoltage protection, the voltage mode is 140 volts AC (rms) continuous, whereas the current mode is 8 volts DC continuous. The 1771-IL features integrated open circuit detection, input overvoltage protection, and auto-calibration. The backplane current rating of this device is 1.3 amperes. It does not need an external power supply unit to function. The 1771-IL has a single slot width and a rack-mountable layout. The Allen Bradley 1771-IL has an operating temperature that should remain within a range of 0 to 60 degrees Celsius, or the equivalent range of 32 to 140 degrees Fahrenheit. The temperature range should be -40 to 85 degrees Celsius, or -40 to 185 degrees Fahrenheit, when storing this device. Additionally, the relative humidity should be 5 to 95 % non-condensing with this device is operational and 5 to 80% non-condensing when being stored.