1769-IA16 — Compact I/O 16-Point 120V AC Input Module

The 1769-IA16 is a 16-point 120V AC digital input module for the 1769 Compact I/O platform. Each input reads a 120V AC field signal — from a pushbutton, limit switch, proximity sensor with AC output, or relay contact in an AC control circuit — and presents the result as a discrete bit in the controller's I/O image. For systems where field devices run on 120V AC control circuits rather than 24V DC, the 1769-IA16 interfaces directly without signal conversion or interposing relays.

Specifications

Parameter	Value
Part Number	1769-IA16
Platform	Compact I/O (1769)
Input Points	16
Input Voltage	100–132V AC (nominal 120V AC)
Input Frequency	47–63 Hz
ON-State Voltage	74–132V AC
OFF-State Voltage	0–20V AC
Input Current (at 120V)	10 mA typical
Input Groups	2 × 8 points, shared AC common per group
Input Filter	Software selectable: 1, 2, 9 ms
Backplane Current (5V)	100 mA
RTB	1769-IA16 requires SCREW terminal base (included or separate)
Operating Temperature	0°C to 60°C
Standards	UL 508, CE, IEC 61131-2

AC Input Modules in Mixed-Voltage Systems

Industrial plants built before the 24V DC sensor standard became dominant frequently used 120V AC control circuits throughout — pushbuttons, limit switches, selector switches, and relay contact signals all running on the same 120V AC distribution that feeds motor starters and pilot lights. Retrofitting these systems to 24V DC is expensive and time-consuming. The 1769-IA16 allows a modern Compact I/O-based controller to integrate with existing 120V AC field devices directly, preserving the installed wiring while upgrading the control logic to a programmable platform.

The two groups of eight inputs each share an AC common terminal. Both groups must be connected to the hot and neutral of the 120V AC supply — the shared common is the neutral (L2) reference. All 16 inputs on one module must therefore come from the same 120V AC phase and neutral. Mixing inputs from different phase-neutral pairs on the same module creates a neutral conflict that can cause false readings or circuit damage.

Wiring Notes

Connect the L2 (neutral) terminal to each group's common terminal. Input signals connect between the input terminals and the L1 (hot) side through the field device contacts.
The input filter (1, 2, or 9 ms, set in Studio 5000) determines how long the AC signal must be present before the module registers the input as ON. At 60 Hz, one half-cycle is 8.3 ms — the 9 ms filter requires approximately one full cycle before registering, providing good noise rejection. At 1 ms, the module responds faster but is more susceptible to transient noise from adjacent contactors or inductive switching.
Input leakage current at the OFF state can be 1–2 mA — adequate to hold some solid-state relay loads in a partially ON state. Verify any output devices driven from downstream solid-state relays have a minimum load resistor if false ON states in the OFF condition are suspected.

FAQ

Q: Can 240V AC inputs be used with this module?

No. The 1769-IA16 is rated for 100–132V AC. Applying 240V AC to these inputs will exceed the voltage rating and damage the input circuitry. For 240V AC inputs, a module specifically rated for that voltage range is required.

Q: Can the two input groups connect to different AC circuits from different phases?

Only if the circuits share the same neutral reference. If the two groups connect to different phase-to-neutral circuits (e.g., L1-N and L2-N from a split-phase supply), the neutral commons are typically shared and this is acceptable. Connecting groups to circuits with isolated neutrals or different transformer secondaries creates undefined common-mode conditions — not recommended.

Q: Why would a 120V AC input module be preferred over a 24V DC module with interposing relays?

Direct connection eliminates interposing relay hardware, relay panel space, relay coil power consumption, and the additional failure mode of relay contacts. In retrofits where field wiring is already 120V AC and cannot be changed, the AC input module is also significantly less expensive and less labor-intensive than rewiring to 24V DC at the field devices.

Q: Does the module work on 50 Hz power systems as well as 60 Hz?

Yes. The module operates at 47–63 Hz, covering both 50 Hz and 60 Hz supply frequencies. Input filtering behavior is specified at 60 Hz; at 50 Hz, the half-cycle duration is longer (10 ms vs 8.3 ms), which slightly affects how the filter interacts with AC signals — the 9 ms filter may register more reliably at 50 Hz since one full 50 Hz cycle is 20 ms.

1769-IA16 New Compact I/O 16 PT. PLC Input Module 120VAC Ser A 1769IA16