Allen Bradley 1756-IF8IH ControlLogix HART Analog I/O Module

The Allen Bradley 1756-IF8IH is a HART Analog I/O Module with 8 current inputs available, with 1 HART modem per channel. This input module is compatible with the ControlLogix system and requires an RTB, or removable terminal block housing, which can either be the 1756-TBCH or the 1756-TBS6H.

The module has two input ranges you can choose from and these are from 0 to 20 milliamps or 4 to 20 milliamps, with HART instruments using the latter (4 to 20 milliamps) range. You can also select one of the four data formats available for this module: analog only, analog and HART PV, analog and HART by channel with Configure HART device (No), and analog and HART by channel with Configure HART device (Yes). Its resolution range is fixed from 16 to 21 bits. This module works as a HART master, as it communicates with HART devices that have a HART revision of 5, 6, or 7. It also supports 1 HART device per channel but does not support burst mode, phase shift keying (PSK), or a multi-drop network configuration. Instead, it detects and turns off a bursting device at an initial connection with the device. The 1756-IF8IH has detection features available. It can detect under-ranging and over-ranging, or when it is operating beyond the limits of the input range. An open circuit detection is also present and this allows the module to report a negative full-scale value in the input data tag of the channel within 5 seconds in the 4 to 20 milliamp range, and in the 0 to 20 milliamp range, the open-circuit condition results in a measured value of 0 milliamps, the same as a measured value of 0 milliamps when there is not an open-circuit condition.

The module filter of the 1756-IF8IH attenuates the input signal at the specified frequency and above, as each channel has an ADC filter that affects 50 and 60 Hertz rejection, noise accuracy, and the minimum sample time (RTS). It also has a digital filter that reduces the noise transients of the input data. Each channel has a separate digital filter. Real-time sampling is available with the 1756-IF8IH and this instructs the module how often it should scan its input channels and get new sampled data. After these channels are scanned, the data will be broadcasted by the module to the local chassis backplane.

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Specification Sheet .pdf