1734-OX2 — POINT I/O 2-Point Relay Output Module

The 1734-OX2 is a two-point relay output module for the 1734 POINT I/O system. Each point is an isolated Form C (NO + NC) relay contact, rated at 240V AC or 125V DC, 2A. Two independent relay circuits in a single 1734 module slot — useful when a POINT I/O node needs to switch AC or mixed-voltage loads that transistor output modules can't handle.

POINT I/O is a distributed I/O system designed for mounting close to field devices, typically on a DIN rail inside a local enclosure near the machine. The 1734-OX2 fits into this architecture naturally — wherever a POINT I/O node needs to switch a contactor coil, a solenoid valve at line voltage, or a pilot light running on a different supply from the control system, these two relay points handle it without needing a separate relay module or interposing relay.

Specifications

Parameter	Value
Part Number	1734-OX2
Platform	POINT I/O (1734)
Output Points	2 (isolated, Form C)
Contact Configuration	NO + NC per point
Output Voltage (AC)	Up to 240V AC
Output Voltage (DC)	Up to 125V DC
Output Current (resistive)	2 A per point
Minimum Load	10 mA @ 5V DC
Electrical Life (full load)	500,000 operations
Mechanical Life	10 million operations
Backplane Current (5V)	75 mA
Backplane Current (24V)	95 mA
Operating Temperature	−20°C to 55°C
Standards	IEC 61131-2, UL 508, CE

Relay Output vs. Transistor Output — Choosing the Right Type

POINT I/O offers both transistor (solid-state) and relay output modules. Transistor outputs switch faster, last longer in high-cycle applications, and generate no contact bounce — but they're limited to 24V DC loads and can't switch AC circuits. Relay outputs switch any voltage up to 240V AC or 125V DC and can mix AC and DC loads across points, but they have mechanical wear limits and slower switching speeds.

The 1734-OX2 makes sense when: the load runs on a voltage other than 24V DC, the load is an AC solenoid or contactor coil, the application needs NO and NC contacts from the same output point, or the cycle rate is low enough that contact wear isn't a concern (500,000 full-load operations equals roughly 100 cycles per hour over 5 years of continuous operation).

For high-frequency switching — more than 10–20 cycles per minute on the same output — transistor outputs with interposing relays typically outlast direct relay outputs and often work out cheaper over the machine's lifetime.

Contact Life in Practice

The 500,000 operation electrical life rating applies at full load (2A, 240V AC resistive). Real-world contact life varies significantly with load type and current level:

Resistive loads at low current — contact life often exceeds the rated figure considerably. A 24V DC LED indicator drawing 50 mA imposes almost no wear per operation.
Inductive loads (solenoids, coils) — the inductive arc on opening degrades contacts faster than resistive loads. Suppressors reduce this substantially; always fit them on inductive loads.
Motor loads (AC-3 duty) — motor inrush current on closing and back-EMF on opening both stress contacts. Use the AC-3 derating curve (not the resistive rating) to determine actual life at the motor's full-load current.

FAQ

Q: Can the 1734-OX2 switch 277V AC loads?

No. The maximum rated voltage is 240V AC. For 277V AC switching, a relay with appropriate voltage ratings is required outside the POINT I/O system.

Q: Are the two relay points individually addressable in the controller?

Yes. Each point maps to a separate output bit in the controller's I/O image. They operate completely independently — one can be on while the other is off.

Q: What POINT I/O adapter modules is the 1734-OX2 compatible with?

The 1734-OX2 is compatible with all 1734 POINT I/O adapter modules — EtherNet/IP (1734-AENT), DeviceNet (1734-ADN), ControlNet (1734-ACN), and others. The relay module itself is protocol-agnostic; compatibility is determined by the adapter at the head of the POINT I/O node.

Q: Can I replace a 1734-OX2 without removing adjacent modules?

Yes. POINT I/O modules use individual removable terminal bases. The terminal base stays wired in place; the module body snaps out for replacement without disturbing adjacent modules or their wiring.

Q: Is there a version with more than two relay points in a single module?

The 1734-OX2 is the standard 2-point relay module for POINT I/O. Adding more relay points means adding additional 1734-OX2 modules to the node — POINT I/O's modular architecture makes this straightforward without requiring a fixed-size I/O card.

1734-OX2 POINT I/O 2 Point Output Module Original Sealed 1734OX2