Allen-Bradley 1794-IE8H Flex I/O HART Analog Input Module

Allen-Bradley 1794-IE8H Flex I/O HART Analog Input Module

Product Introduction

The Allen-Bradley 1794-IE8H is a high-performance analog input module from the Flex I/O family. Specifically, it features eight single-ended, non-isolated input channels. This module supports standard analog signals like 0-20 mA and 4-20 mA. Additionally, it integrates HART communication protocol support. The 1794-IE8H allows you to access transmitter data and diagnostic information directly. Therefore, this capability makes it an excellent choice for modern process automation systems.

Technical Specifications

The 1794-IE8H provides eight single-ended analog inputs. For instance, it supports current signal ranges of 0-20 mA and 4-20 mA. The default input range is 0-20 mA. Moreover, users can configure each channel individually for flexibility.

Resolution is a key strength of this module. For example, it offers 16-bit resolution for unipolar configurations and 15-bit for configurations handling both positive and negative signal ranges. Absolute accuracy is 0.1% of Full Scale at 20 °C (68°F). Furthermore, accuracy drift with temperature is only 0.05% of Full Scale across the 0 °C to 55 °C range. Consequently, this ensures reliable measurements in varying conditions.

The 1794-IE8H integrates a local microprocessor. In fact, this processor handles advanced features without burdening the main controller. It supports multiple data formats and ranges. Meanwhile, the module includes comprehensive alarm functions. These include lead breakage detection, overrange and underrange alarms, and remote transmitter alarms.

The module requires an external DC supply. Specifically, the nominal voltage is 24V DC, with a range of 19.0 to 31.2V DC (including 5% AC ripple). The typical current draw is 295 mA at 24V DC. Meanwhile, the FlexBus current draw is 80 mA at 5V DC and 190 mA at 24V DC.

The step response time to 99% of final value is 80 ms. Additionally, the isolation voltage is rated at 50V continuous between the field side and the system. Basic insulation type is routine tested at 850V DC for 1 second.

HART Protocol Support

A standout feature of the 1794-IE8H is its HART communication capability. For instance, HART (Highway Addressable Remote Transducer) is an open protocol. Specifically, it enables bidirectional communication with smart field instruments. Through the 1794-IE8H, you can access additional process variables. Moreover, you can also perform diagnostics and configure connected HART devices. This integration reduces the need for separate HART multiplexers. Furthermore, it simplifies wiring and lowers overall system costs.

The 1794-IE8H is compatible with several Flex I/O communication adapters. These include ControlNet, Ethernet, and ProfiBus adapters. However, note that for ProfiBus, only catalog number 1794-APBDV1 is compatible. ControlNet revision 5.1 or greater is required. Similarly, Ethernet revision 4.2 or greater supports Series B HART modules.

Mechanical and Environmental Parameters

The 1794-IE8H is designed for rugged industrial environments. First, its operating temperature range is from -20 °C to +55 °C (-4 °F to +131 °F). Second, the non-operating temperature range is -40 °C to 85 °C. Furthermore, it withstands operating vibration of 2 g at 10 to 500 Hz. Operating and non-operating shock resistance is rated at 15 g.

Maximum power dissipation is 3.9W at 31.2V DC. Meanwhile, thermal dissipation is 13.5 BTU/hr under the same conditions. The module has an open-style enclosure and does not require an additional housing.

Status Indicators

The 1794-IE8H provides clear visual status feedback. Specifically, it features:

• 8 red fault indicators – one per channel to signal errors

• 8 yellow channel indicators – show active channel status

• 1 green power indicator – confirms module power is present

Therefore, these indicators simplify troubleshooting and reduce maintenance downtime.

Compatible Terminal Bases

The 1794-IE8H requires a compatible terminal base for installation. In particular, it works with the following terminal base units:

• 1794-TB3G

• 1794-TB3GS

Thus, select the appropriate base based on your wiring and installation needs. The terminal base determines the wire size and connection method.

Installation Guide

Installing the 1794-IE8H is a straightforward process. First, mount the compatible terminal base (1794-TB3G or 1794-TB3GS) onto a DIN rail. Next, snap the 1794-IE8H module onto the terminal base. Ensure it clicks securely into place.

Connect your analog field devices to the terminal base according to the wiring diagram. Meanwhile, pay attention to the single-ended wiring configuration. Connect the external DC power supply to the designated terminals. Finally, connect the communication adapter to complete the Flex I/O assembly.

Remember to power down the system before installation. Moreover, verify all connections are secure before applying power. After power-up, check the green LED to confirm normal operation.

Configurable Features

The 1794-IE8H offers several user-configurable settings. For example, these include:

• Input filter cutoff frequency

• Fault mode behavior

• Data format selection (including unipolar and dual-polarity signal formats)

• High and low error level thresholds

• Remote transmitter error correction

Configuration is performed through the communication adapter. In fact, no physical switches or jumpers are required on the module itself. Therefore, this software-based approach simplifies setup and allows for easy adjustments.

Packaging List

Your shipment for the Allen-Bradley 1794-IE8H includes:

• (1) Allen-Bradley 1794-IE8H Flex I/O HART Analog Input Module

• (1) Installation Instructions manual

The module is packaged in an anti-static bag for safe transport.

Shipping Information

All orders are shipped via premium courier services. Your 1794-IE8H will be dispatched using FedEx, UPS, or DHL. Moreover, you will receive tracking information once your order ships.

Frequently Asked Questions (FAQ)

1. What types of signals can the 1794-IE8H accept?
The 1794-IE8H accepts analog current signals. Specifically, it supports both 0-20 mA and 4-20 mA input ranges. Additionally, each channel can be independently configured for the desired range.

2. What is the advantage of HART support on this module?
HART support allows the 1794-IE8H to communicate digitally with smart transmitters. For instance, you can access secondary variables, run diagnostics, and reconfigure devices. Therefore, this eliminates the need for separate HART interface hardware.

3. Which terminal bases are compatible with the 1794-IE8H?
The 1794-IE8H is compatible with terminal bases 1794-TB3G and 1794-TB3GS. Consequently, choose the base that best fits your wiring and installation preferences.

4. How accurate is the 1794-IE8H over temperature changes?
The 1794-IE8H offers excellent accuracy. For example, it has a drift of only 0.05% of Full Scale from 0 °C to 55 °C. Thus, this ensures stable and precise readings even in changing ambient conditions.

5. Does the 1794-IE8H provide isolation between input channels?
No, the input channels on the 1794-IE8H are non-isolated. However, the module does provide 50V continuous isolation between the field side and the system side. Therefore, this protects the control system from field wiring faults.