1769-L23E-QBFC1B — CompactLogix L23 Controller with Onboard I/O, EtherNet/IP, and SD Card

The 1769-L23E-QBFC1B is a CompactLogix L23 series controller with a substantial amount of hardware packed into one housing. Beyond the CPU and power supply, it includes 16 digital inputs (24V DC), 16 digital outputs (relay), two analog inputs, two analog outputs, an embedded EtherNet/IP port, two serial ports (RS-232/485), and an SD card slot for program backup. For small to mid-range machines, this single unit covers a complete controller, I/O, and communication package without a single expansion module required at the start.

The L23 family sits between the Micro800 series and the larger CompactLogix L3x/L4x in terms of capability. It runs the full Studio 5000 / RSLogix 5000 programming environment, supports IEC 61131-3 languages including structured text and function block, handles motion control (basic axis control via analog output), and connects to the broader ControlLogix ecosystem over EtherNet/IP. For OEM machine builders who want a capable, networkable controller with minimal hardware to specify and install, it's a well-proportioned starting point.

Specifications

Parameter	Value
Part Number	1769-L23E-QBFC1B
Series	CompactLogix L23
Onboard Digital Inputs	16 × 24V DC (sourcing/sinking)
Onboard Relay Outputs	16 × relay (Form A, 240V AC / 30V DC, 2A)
Onboard Analog Inputs	2 × 0–10V / 0–20 mA (selectable)
Onboard Analog Outputs	2 × 0–10V / 0–20 mA (selectable)
Total Onboard I/O	36 points
Expansion I/O	Up to 16 × 1769 Compact I/O modules
Communication Port 1	EtherNet/IP (10/100 Mbps, RJ-45)
Communication Ports 2–3	RS-232 and RS-485 (selectable)
Memory	512 KB user program / 512 KB data
SD Card Slot	Yes (program backup, firmware update)
Power Supply	24V DC (19.2–26.4V DC) — external, user-supplied
Operating Temperature	0°C to 60°C
Standards	UL 508, CE, cUL, IEC 61131-3

Getting Started Quickly

First-time setup with the L23 follows a cleaner path than building a modular system from scratch. The essentials:

Connect 24V DC to the controller's power input terminals. The controller, the onboard I/O, and the analog circuits all draw from this single supply.
Set the IP address — either via BOOTP from a BOOTP server on the network, or by pressing and holding the SET button on the controller to access the built-in BOOTP/DHCP/static IP selector mode.
Open Studio 5000 (or RSLogix 5000 for older versions), create a new project, and select the 1769-L23E-QBFC1B as the controller. The onboard I/O is pre-configured in the project template; no separate I/O module addition is needed for the base I/O.
Wire field devices to the terminal screws on the controller housing. Input commons, output power connections, and analog signal terminals are all labeled on the housing face.
Download the program, go online, and verify I/O in the controller's I/O tree before running the machine.

Expansion and Growth

Up to 16 Compact I/O modules connect to the right side of the controller, adding up to several hundred more digital and analog I/O points depending on module selection. The 1769 bus expansion follows the same architecture as a standalone CompactLogix system — the same module catalog numbers, the same Studio 5000 configuration process, the same wiring conventions.

Remote I/O over EtherNet/IP is also available. FLEX I/O nodes, POINT I/O nodes, or additional CompactLogix systems can join the EtherNet/IP network and present their I/O to this controller. The L23 manages this remote I/O the same way a CompactLogix L3x does — the controller tier is consistent, even if the L23 is at the lower end of the CompactLogix family.

The onboard relay outputs are Form A (normally open) contacts. If normally closed output contacts are needed in the application, either use interposing relays external to the controller, or add a 1769-OW8 relay output expansion module that provides a mix of NO and NC contacts per output point.

FAQ

Q: Does this controller require a separate 24V DC power supply module?

Yes. The L23 requires an external 24V DC supply connected to its power input terminals — it does not include an AC-to-DC power supply internally. A 1606-series or equivalent industrial DIN rail supply is appropriate. Size the supply for the controller's own consumption plus the field power requirements of the onboard I/O.

Q: Can the analog I/O be configured for different ranges per channel?

Each of the two analog inputs and two analog outputs is configurable independently in Studio 5000. One channel can be 0–10V while another is 4–20 mA — the configuration is per-channel, not per-module.

Q: Is this controller compatible with the 1769 Compact I/O modules used with a CompactLogix L3x system?

Yes. The L23 uses the same 1769 expansion bus as other CompactLogix controllers. Any 1769 Compact I/O module that is compatible with the L23's firmware revision works as an expansion module.

Q: What is the SD card used for?

The SD card stores the controller program and can be used for automatic program loading on power-up, firmware updates, and data logging (event logs, fault history). It is not required for normal controller operation — the program runs from internal flash memory.

Q: Can the RS-485 port communicate with third-party devices using Modbus RTU?

Yes. The serial ports support ASCII, DF1, DH-485, and Modbus RTU protocols. Modbus RTU master operation is available through the MSG instruction in the program. Many drives, instruments, and sensors with Modbus RTU slave interfaces connect this way.

1769-L23E-QBFC1B New In Box Controller Unit CPU Module 1769L23EQBFC1B