AB 1794-IF8IH FLEX I/O Isolated Input HART Analog Module

AB 1794-IF8IH FLEX I/O Isolated Input HART Analog Module

IMPORTANT USER INFORMATION: Solid-state equipment has different characteristics than electromechanical equipment and should be used in accordance with applicable safety guidelines to ensure application compliance. Rockwell Automation is not responsible for consequential damages arising out of the use of the equipment. The manual examples are for reference only and may not be reproduced without permission. The manual includes a variety of safety tips, such as operating in hazardous environments, risk of electric shock and burns, and more.

Installation requirements: For industrial environments in pollution class 2, overvoltage category II, up to 2000 metres above sea level, Group 1, Class A industrial equipment. Installation in a suitable enclosure which is flame retardant and accessible only by means of tools, with attention to electromagnetic compatibility. Use zinc-plated yellow chrome steel DIN rails for grounding, avoiding corrosive, oxidised or poorly conductive rail materials.

Hazardous area approvals

North America: The module is approved for use in hazardous areas in North America. The product is labelled with a temperature code, and when combining devices, attention should be paid to the overall temperature code and the local regulatory review, and it is strictly prohibited to electrically disconnect the device or make connections when operating in hazardous areas.

Europe: The module is approved for use in potentially explosive environments in Europe Zone 2, with additional requirements for use, such as UV protection, enclosure protection levels, and avoidance of voltage overruns.

Installation steps

Installation to Terminal Block: Install the module in the 1794 - TB3 or 1794 - TB3S terminal block, before installation, turn the key switch to position 3, make sure the Flexbus connector is fully extended, when inserting the module, pay attention to align the grooves and install it securely to prevent debris from falling into the module, as plugging and unplugging with electricity may be dangerous.

Wiring: Connect the input, signal return, power and common wires to daisy chain the power supply. Use shielded wires and connect them to functional ground, which varies for different types of transmitters.

Grounding: All I/O wiring must be shielded and the shield must be grounded on the outside of the module.

Module Configuration: Set module parameters such as byte order, digital filter, fault mode, HART current ratio, etc. through the configuration mapping table, different settings correspond to different functions and value ranges. There are various choices of data format, such as milliamps, percentage of full scale, etc. Some formats only support HART communication.

HART input data: HART input data contains the main variables and other information of the device, and HART communication can be disabled through configuration.HART input data word contains information of communication status, device status, variable acquisition, etc., and each status bit has a clear meaning.

Status Indicator: OK The status indicator is bicolour (red/green). Flashing green indicates that the module configuration word is zero, the 24V DC user power supply is off, or the module is in configuration mode; red indicates that the module has not passed the initial hardware test, and the module needs to be re-powered when the red indicator appears.

Basic Parameters

Number and type of inputs: 8 single-ended, isolated analogue input channels, which can effectively avoid inter-channel interference and is suitable for industrial scenarios requiring isolated inputs.

Recommended Terminal Block: For 1794-TB3 and 1794-TB3S terminal blocks to ensure stability and compatibility of the module with external devices.

Key switch position: 3, the module can be adapted to the corresponding operating mode by setting a specific key switch position.

Enclosure type rating: None (open), which means that the module can be used in an additional protective enclosure to meet the protection requirements of the specific application.

Electrical parameters

Resolution and Data Format: Resolution is 16-bit unipolar or 15-bit plus sign bit bipolar, with a current resolution of 0.320 µA/cnt in unipolar and 0.640 µA/cnt in bipolar. The data format supports engineering units, percentage full scale, and RAW/proportional counting to meet different data processing and display requirements.

Conversion related: Sigma Delta conversion type is adopted, and the conversion rate varies according to different settings, such as 4.17Hz, 10.0Hz, 16.7Hz, 19.6Hz, 62Hz, 470Hz, etc., in order to adapt to different measurement frequency requirements. Input current can be configured as 4 - 20mA or 0 - 20mA, output 0mA when not configured.

Accuracy and immunity: Absolute accuracy 0.1% full scale at 25°C, accuracy drift 0.4% full scale from 0 - 55°C. Under normal mode, it has high rejection ratio for current signals of different frequencies, and the common mode rejection ratio is more than 60dB at 50Hz and 60Hz, which has good anti-interference ability.

Input Characteristics: The input resistance is 249Ω ±1%, which can acquire the input signal stably. The maximum overload is 32mA continuous (one channel at a time) to ensure the safety of the module under certain overload conditions.

Isolation and power supply: Isolation voltage is 120V (continuous), basic insulation type, tested by 1000V AC for 60s, including isolation between user power supply and system, channel and system, and channel and channel.Flexbus current is 80mA @ 5V DC, used to supply power to the Flexbus interface of the module; maximum power consumption is 4.8W at 31.2V DC, and maximum heat dissipation is 16.4BTU. Maximum power consumption is 4.8W at 31.2V DC and maximum thermal dissipation is 16.4BTU/hr; external power supply requirements are 24V DC (19.2-31.2V DC with 5% AC ripple) and supply current is 190mA at 24V DC.

Physical Parameters

Dimensions: Measures approximately 94 x 94 x 66mm (3.7 x 3.7 x 2.6in.) when mounted for easy installation in a facility.

Indicator Lights: Equipped with 1 red/green power/status indicator light, which reflects the working status of the module through different colours and blinking status, e.g. blinking green indicates that the module's configuration word is zero, the power is off, or it is in the configuration mode, while red indicates that it has not passed the initial hardware test.

Wire-related: Wire size is determined by the installed terminal block, shielded wires are required, wiring category is divided into signal port category 2, power port category 3, which can be used for planning wire routing, and the grounding conductor should be equal to or greater than the phase conductor.