1756-IF8I Allen Bradley ControlLogix analog input module

This module is installed to any ControlLogix chassis whether local, distributed or remote I/O installation. It requires 1756-TBCH and 1756-TBS6H Removable Terminal Blocks for signal wiring and appropriate wire size range for this module is 0.33 to 2.1 mm2 (22 to 14 AWG) solid or stranded shielded copper wire.

The Allen-Bradley 1756-IF8I is an Eight (8) Point General-Purpose Isolated Analog Current/Voltage Input Module. It requires a 36-pin Removable Terminal Block (RTB) before it can be wired with input signals. The 1756-IF8I provides higher-level accuracy through its 24-Bit conversion resolution and supports 2-wire or 40Wire transmitter configuration.

This module does not offer the Real-Time Sampling (RTS) parameter and the channel sampling rate is exclusively determined by the requested packet interval (RPI) value. This module has input ranges and actual resolution of -10 to 10 Volts with 1.49 Volts/count, 0 to 10 Volts with 1.49 ?Volts/count, 0 to 5 Volts with 1.49 ?Volts/count, and 0 to 20 milliamps with 2.99 nA/count. It should be noted that the source current is limited to about 45 milliamps and is capable of powering a two-wire transmitter directly without needing an external power supply.

An under-range/over-range detection feature is present in the 1756-IF8I. This enables the module inform process operator or maintenance personnel that the specific channel has received an input signal below the nominal value. This module also has process alarm and rate alarm features. Process alarms are triggered when the module has exceeded the configured high or low limits in every channel. Rate alarms, on the other hand, are triggered when the rate of change between input samples for every channel exceeds the specified trigger point for that particular channel. It also has an analog-to-digital converter (ADC) that is used to remove the line noise, known as noise immunity, in your application for every channel. The notch filter reduces the amplitude of the signal with minimal signal distortion. Aside from that, a digital filter is also present, and this smooths input data noise transients on each input channel. The 1756-IF8I’s synchronized sampling feature allows synchronization of input sampling across inputs on multiple modules, which forces the inputs to sample simultaneously within around 20 ?S of each other, even if the modules do not belong to the same chassis as long as the system clocks are synchronized through the CIP Sync. The module’s sensor offset feature compensates for any known error on the channel to which the sensor is connected to or the sensor itself. A wire off detection feature is also present to detect when a wire lost connection with a channel or an RTB has been removed from the module.