1734-OB2EP — POINT I/O 2-Point 24V DC Protected Transistor Output Module

The 1734-OB2EP is a two-point sourcing (PNP) 24V DC transistor output module for the 1734 POINT I/O system, with individual electronic short-circuit and overload protection on each point. The "EP" suffix identifies the electronic protection — each output has its own protection circuit that shuts down only that point on a fault, leaving the other output unaffected and reporting a fault bit back to the controller.

Two protected outputs in one POINT I/O slot is a sensible combination for distributed nodes where each controlled device deserves its own protected switching point and fault diagnostics matter. In valve-heavy process systems, a solenoid fault on one output shouldn't kill the adjacent output — and knowing exactly which point has faulted saves the maintenance technician a circuit-tracing exercise. The 1734-OB2EP provides both.

Specifications

Parameter	Value
Part Number	1734-OB2EP
Platform	POINT I/O (1734)
Output Points	2
Output Type	Sourcing (PNP) transistor
Output Voltage	24V DC (10–30V)
Output Current per Point	2 A continuous
Short-Circuit Protection	Electronic, per point (individual)
Overload Protection	Yes, per point — auto-reset when fault clears
Fault Reporting	Per-point fault status bits in I/O data
Leakage Current (OFF state)	0.5 mA max
ON-State Voltage Drop	0.4V DC max
Backplane Current (5V)	75 mA
Backplane Current (24V)	95 mA
Operating Temperature	−20°C to 55°C
Standards	UL 508, CE, IEC 61131-2

2 A per Point — Higher Current Than Standard POINT I/O Outputs

Most POINT I/O transistor output modules are rated at 0.5A per point. The 1734-OB2EP is rated at 2A per point — four times the current capacity. This expands the range of loads that can be switched directly without an intermediate relay or current-booster circuit.

At 2A, the module handles loads that standard 0.5A modules cannot reliably drive: larger solenoid valves (many direct-acting 1/2-inch solenoids draw 0.8–1.5A), resistive heater elements up to 48W on 24V, multiple LED indicators wired in parallel, and 24V coil contactors for larger motor starters. For applications where the load current per point is between 0.5A and 2A, the 1734-OB2EP removes the need for an interposing relay that would otherwise be required.

Per-Point Diagnostics — Turning Fault Bits Into Useful Information

When an output on the 1734-OB2EP trips — due to a short circuit, overload, or open load (if configured) — a fault bit is set in the module's input data for that specific point. The controller program can read this bit and take action:

Set an alarm tag that triggers an HMI popup identifying the specific output point and the device wired to it.
Inhibit a machine sequence that depends on that output — preventing the machine from continuing to operate without the faulted device functional.
Log the fault time and output number to a data file for maintenance records.
Attempt an automatic restart of the output after a time delay — useful for outputs that may trip transiently from brief inrush or transient load conditions.

The diagnostic value depends entirely on what the controller program does with the fault bits. Leaving them unmapped to any alarm or action means the protection still works, but the diagnostic benefit is lost. Map the fault bits to named alarm tags in Studio 5000 at commissioning — it takes a few minutes and pays for itself the first time a field technician finds the faulted device in under a minute instead of twenty.

FAQ

Q: When an output trips on overload, does it reset automatically?

Yes, once the fault condition clears — the overcurrent path is removed. Whether the output then re-energizes depends on the controller program's output logic. If the output tag is still set to 1, the output will come back on automatically when the fault clears. If automatic restart is not desired, the program should monitor the fault bit and clear the output tag until an operator acknowledges the fault.

Q: Is this module a drop-in replacement for a standard 1734-OB2 (non-protected) module?

Electrically and physically, yes — same wiring, same terminal base, same slot footprint. The added per-point protection and fault reporting are additive features. The controller program may need to add logic to handle the fault status bits if proactive fault monitoring is desired, but the basic output function works identically.

Q: Can the two output points switch different load voltages?

Both outputs source from the same field supply connected to the terminal base. They cannot independently switch different voltage levels — both operate at the same supply voltage. For switching different voltages on the same node, relay output modules (1734-OW2 or 1734-OX2) provide isolated contacts that can handle different circuit voltages per point.

Q: What POINT I/O adapter modules are compatible?

All standard 1734 adapters — EtherNet/IP (1734-AENT), DeviceNet (1734-ADN), ControlNet (1734-ACN), and others. The output module is protocol-agnostic and works with any adapter that supports the POINT I/O backplane.

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