1794-OF8IH Isolated 8-Channel 4-20mA Output Allen-Bradley

1794-OF8IH Allen-Bradley Flex I/O Isolated HART Analog Output Module

• Eight isolated outputs offer independent configuration for 0‑20 mA or 4‑20 mA. Each channel avoids ground loops and interference.
• Module resolution reaches 16 bits (unipolar). Actual resolution equals 0.305 µA per count for fine current control.
• Conversion method uses a 16‑bit digital‑to‑analog converter. Conversion rate runs at 10 ms for fast updates.
• Channel settling time equals 70 ms. This ensures stable output after a change.
• Data formats include Engineering Units, Percent of Full Scale, and RAW/Proportional Count. You program each channel independently.
• The module detects lead breakages. It also triggers alarms for overrange and underrange current conditions.
• No external power supply is required for operation. The module draws FlexBus current of 80 mA at 5V DC.
• Maximum power dissipation equals 5.0 W @ 24V DC. Thermal dissipation reaches 17.06 BTU/hr @ 24V DC.
• Operating temperature ranges from 32°F to 131°F (0°C to 55°C). This suits most industrial environments.
• The module supports pass‑through messages with 1 or 2 connections. Each connection handles 8 queues for HART communication.
• A dedicated 6‑WORD register stores HART data. It includes Field Device status, HART Communication, Loop Status, and primary value in IEEE 754‑1985 32‑bit float.
• Factory calibration eliminates manual adjustments. No jumpers or switches are needed for setup.

Terminal Base & Installation Requirements

• Use terminal bases 1794-TB3 or 1794-TB3S with this module. These bases provide secure connections for field wiring.
• Set the keyswitch to position 4 when installing the 1794-OF8IH. This locks the module to the terminal base properly.
• Mount the module on a DIN rail or panel. The Flex I/O system allows easy snap‑on installation.
• Wire type depends on your chosen terminal base. Follow standard analog signal wiring practices for best noise immunity.
• Allow proper ventilation around the module. Keep ambient temperature within 0°C to 55°C (32°F to 131°F).
• The module communicates through the FlexBus. No separate external 24V DC supply is needed for the outputs.

Frequently Asked Questions (FAQ)

• Q: Is the 1794-OF8IH a genuine Allen‑Bradley new module?
  A: Yes, we supply 100% brand new and original Allen‑Bradley 1794-OF8IH modules. No used or imitation products.
• Q: What terminal bases work with the 1794-OF8IH?
  A: This module fits 1794-TB3 and 1794-TB3S terminal bases. Use keyswitch position 4 for proper installation.
• Q: Does the 1794-OF8IH require an external 24V DC power supply?
  A: No, the module draws power from the FlexBus (80 mA @ 5V DC). No external supply is needed for operation.
• Q: What is the conversion rate and resolution?
  A: Conversion rate is 10 ms using a 16‑bit DAC. Resolution equals 16 bits unipolar or 0.305 µA per count.
• Q: Does the module support HART communication?
  A: Yes, the 1794-OF8IH provides HART pass‑through messaging. It uses a dedicated 6‑word register for HART data including primary variable in IEEE 32‑bit float.
• Q: Do you have stock available? How long until delivery?
  A: Yes, we keep stock on hand. Shipment occurs within 5 days after order. Delivery time depends on your location and chosen courier (FedEx, UPS, DHL).
• Q: What is the return policy?
  A: We offer 30 days return from delivery date. Items must be unused and in original packaging. Contact us for RMA authorization.
• Q: Can I calibrate the 1794-OF8IH manually?
  A: The module ships factory calibrated. No field calibration is required. Jumpers and switches are not needed for configuration.
• Q: What alarms does the module provide?
  A: It detects lead breakages and generates alarms for overrange and underrange current conditions. This enhances diagnostic capability.

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