Allen-Bradley 1738-OB8EM8 ArmorPoint I/O Output Module

The Allen-Bradley 1738-OB8EM8, also cataloged as the 1738-OB8EM8 DC Output Module, operates as a dedicated hardware component for 24 V DC discrete load switching within ArmorPoint distributed I/O networks. Configured for non-isolated sourcing output execution, the Allen-Bradley 1738-OB8EM8 provides direct electrical actuation of 8-channel digital loads through M8 connector interfaces under a nominal 24 V DC control architecture.

Suffix Breakdown & Model Matrix

The model 1738-OB8EM8 is structured as follows:

• 1738: ArmorPoint I/O platform identifier

• OB8: 8-point output module configuration

• EM8: M8 (Pico) connectorized field interface variant
  No additional sub-encoding is defined for channel grouping or electrical segmentation.

Hardware Specifications

Backplane Deterministic Output Execution and I/O Scaling

Within the ArmorPoint architecture, the 1738-OB8EM8 executes output state transitions via PointBus synchronized backplane communication. Each channel is updated in deterministic cycles with group-based output handling (1 x 8-channel block). I/O density scaling is governed by backplane current distribution and module-level thermal dissipation under sealed IP-rated housing constraints. Non-isolated channel grouping imposes shared reference potential across all outputs.

Frequently Asked Questions (FAQ)

Q: Does the 1738-OB8EM8 support hot-swapping under load conditions?
A: Yes, RIUP is supported. However, all 8 outputs are forced to a de-energized state during module removal and reinitialization of the PointBus interface.

Q: Are the output channels individually isolated?
A: No. All 8 outputs are non-isolated and share a common sourcing reference within a single output group.

Q: What is the impact of exceeding 28.8 V DC on output channels?
A: Operation beyond 28.8 V DC exceeds rated limits and may cause output driver saturation or permanent switching element degradation.

Field Installation Guidelines

M8 connectors must be fully seated and locked to maintain IP67/IP69K sealing integrity. Output wiring shall maintain separation from high-energy switching conductors to reduce inductive coupling into shared reference lines. Shield termination must be implemented at a single controlled grounding point to avoid circulating ground currents. During installation or replacement, ensure output loads are in a safe de-energized state to prevent unintended actuation during PointBus resynchronization.