1794-OV16 — FLEX I/O 16-Point 24V DC Sinking Transistor Output Module

The 1794-OV16 is a 16-point 24V DC sinking (NPN) transistor output module for the FLEX I/O 1794 platform. Where most industrial output modules source current to the load, this one sinks it — the output terminal is the return path, and the load is connected between the positive supply and the output terminal. It's the standard choice when the field devices or the control system convention requires NPN-type switching.

Sixteen outputs, each rated at 0.5A, organized in groups with shared supply terminals. The FLEX I/O form factor keeps the module compact and slots into any 1794 terminal base alongside adapter modules for EtherNet/IP, DeviceNet, ControlNet, and other networks. For distributed I/O nodes built around NPN field device conventions — common in Asian-manufactured machinery and certain process industries — the 1794-OV16 fits without needing output inversion in software or external signal converters.

Specifications

Parameter	Value
Part Number	1794-OV16
Platform	FLEX I/O (1794)
Output Points	16
Output Type	Sinking (NPN) transistor
Output Voltage	24V DC (10–30V)
Output Current per Point	0.5 A continuous
Output Groups	2 × 8 points, separate supply commons
Leakage Current (OFF state)	1 mA max
ON-State Voltage Drop	1V DC max
Short-Circuit Protection	Electronic, per group
Backplane Current (5V)	200 mA
Field Power	24V DC (user-supplied)
Operating Temperature	0°C to 55°C
Standards	IEC 61131-2, UL 508, CE

Sinking Outputs — When They're the Right Choice

Sourcing and sinking describe the direction of current flow through the output transistor. Sourcing outputs (PNP) provide the positive voltage to the load — current flows out of the output terminal. Sinking outputs (NPN) pull the load to 0V — current flows into the output terminal, with the positive supply connected separately to the load.

Neither is inherently better; the right choice depends on what the load expects and what the existing system convention is. Sinking outputs make sense when:

Field devices are wired for NPN-compatible inputs — load connected to +24V, switching to 0V on the return path.
The machine design originates from a region or manufacturer that uses NPN convention as standard (common in Japanese and Korean industrial equipment).
Intrinsically safe barriers in hazardous location installations require a sinking output configuration on the safe-side controller.
An existing system already wired for NPN is being expanded — adding sinking modules maintains consistency without rewiring existing field devices.

Installation on FLEX I/O

The 1794-OV16 mounts on a 1794 terminal base — the base stays wired in place, and the module body clips in and out for replacement without disturbing field wiring. Select the correct terminal base for the module: the 1794-TB3, 1794-TB3S, or 1794-TBN are the common compatible bases. The terminal base determines wiring style (cage clamp or screw) and the number of available field terminals.

Field power to the terminal base is wired at the base level, not on the module itself. The two output groups get their supply from the terminal base power rails. If different supplies are needed for the two groups, verify the terminal base configuration supports separate power rail connections — not all terminal base types do.

FAQ

Q: Can a sourcing output module be substituted if a sinking module is unavailable?

Not as a direct replacement. Sourcing and sinking modules have opposite current flow directions. Swapping one for the other requires rewiring all load circuits — it is a functional wiring change, not a transparent substitution.

Q: The leakage current is 1 mA — will this cause issues with sensitive loads?

For most industrial loads at 24V DC, 1 mA leakage is negligible. For very sensitive loads — low-power relay coils or electronic circuits with low turn-on thresholds — verify that 1 mA at the operating voltage is below the load's trigger threshold when the output is supposed to be OFF.

Q: Is there per-point fault reporting like the 1794-OB32P?

No. The 1794-OV16 has electronic short-circuit protection per group, not per point. A fault on one output in a group shuts down the entire group of 8, not just the faulted point. For applications where per-point fault isolation matters, the 1794-OB32P is the more appropriate choice.

Q: Which FLEX I/O adapter modules work with the 1794-OV16?

All standard 1794 adapter modules are compatible — EtherNet/IP (1794-AENT), DeviceNet (1794-ADN), ControlNet (1794-ACN), and others. The output module is network-agnostic; it communicates via the FLEX I/O backplane regardless of which adapter is at the node.

Q: Can two 1794-OV16 modules be on the same FLEX I/O node?

Yes. Up to eight modules can be on a single FLEX I/O adapter node (depending on adapter type and current budget). Multiple 1794-OV16 modules can coexist on the same node alongside input modules and other output types.

1794-OV16 New Original Sealed 16 Point Digital Output Module 1794OV16