1756-OF8IH

Description

The 1756-OF8IH is a HART-enabled isolated analog output module from Allen-Bradley, offering 8 channels of current output with integrated open circuit detection and robust electrical isolation.

General Information

• Manufacturer: Allen-Bradley

• Series: ControlLogix

• Module Type: Isolated Analog Output Module with HART

• Channels: 8 current outputs

• Output Signal: 4–20 mA

• Isolation: 250V (reinforced, continuous from outputs to backplane)

Electrical Characteristics

• Output Range: 0–20 mA @ 4–20 mA

• Drive Capability: 50–750 Ω, short-circuit protected

• Open Circuit Detection: Yes (≥ 0.1 mA)

• Overvoltage Protection: ±24V DC

• Load Reactance: 10 µH max

• Resolution: 15-bit across 24 mA (732 nA/bit)

• Data Format: IEEE 32-bit floating point

Performance Parameters

• Module Error: ±0.3% @ 4–20 mA

• Offset Drift: ±3 ppm/°C (72 nA typical)

• Gain Drift: ±4 ppm/°C

• Settling Time:

• <23 ms (HART disabled)

• <100 ms (HART enabled)

• Conversion Method: R-Ladder DAC

• Module Scan Time: ~1 s (all channels HART enabled)

Power Requirements

• Backplane Current Draw:

• 220 mA @ 5.1V DC

• 360 mA @ 24V DC

• External Current Draw: 400 mA @ 24V DC (estimated)

• Power Dissipation:

• Nominal: 6.5 W

• <6.4 W @ 50 Ω

• <6.5 W @ 250 Ω

• <6.7 W @ 750 Ω

Wiring and Connections

• Terminal Type: Screw-/spring-clamp connection

• Terminal Torque: 0.5 Nm (4.4 in-lb)

• Wire Type: Copper

• Wire Category: Category 2 – signal ports

Configuration and Diagnostics

• Keying: Electronic, software-configurable

• HART Support: Yes (pass-through messaging, handhelds, etc.)

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