PLC I/O Terminals

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Buy the Beckhoff EL3124-0018 PLC Module - a programmable logic controller component from Beckhoff's industrial automation platform. Provides reliable process control, I/O interfacing, and communication capabilities for manufacturing and process systems. The Beckhoff EL3124-0018 is a direct drop-in replacement for existing PLC installations.

Beckhoff EL7047 Beckhoff

$674.79

In stock, 27 units

EtherCAT Terminal, 1-channel motion interface, stepper motor, 48 V DC, 5 A, vector control, with incremental encoder

Beckhoff EL3184 Beckhoff

$0.00

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4-ch analog input, �10V/�20mA, 16-bit

Beckhoff KL2809 Beckhoff

$296.67

In stock, 22 units

Bus Terminal, 16-channel digital output, 24 V DC, 0.5 A

Beckhoff KL6021 Beckhoff

$815.13

Only 8 units left

Buy the Beckhoff KL6021 - a genuine Beckhoff industrial automation component engineered for reliable performance in demanding manufacturing and process control environments. The Beckhoff KL6021 is a direct drop-in replacement for existing installations and ships ready for integration.

Beckhoff ZK1090-6191-0050 Beckhoff

$568.53

Only 1 unit left

PLC Direct is not an authorized distributor. We offer a broad range of in-stock products with minimal lead time.

Beckhoff KL1194 Beckhoff

$540.00

Only 6 units left

Buy the Beckhoff KL1194 Terminal/Connector - an industrial wiring component providing reliable electrical connections in control panels. Features robust construction, easy installation, and standard mounting. The Beckhoff KL1194 is a direct replacement for existing installations.

Beckhoff EL2911-2200 Beckhoff

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Buy the Beckhoff EL2911-2200 - a genuine Beckhoff industrial automation component engineered for reliable performance in demanding manufacturing and process control environments. The Beckhoff EL2911-2200 is a direct drop-in replacement for existing installations and ships ready for integration.

Beckhoff KL6583 Beckhoff

$528.13

Only 4 units left

Buy the Beckhoff KL6583 - a genuine Beckhoff industrial automation component engineered for reliable performance in demanding manufacturing and process control environments. The Beckhoff KL6583 is a direct drop-in replacement for existing installations and ships ready for integration.

Beckhoff C6330-0020 Beckhoff

$0.00

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PLC Direct is not an authorized distributor. We offer a broad range of in-stock products with minimal lead time.

Beckhoff AX2526-B900 Beckhoff

$1,341.93

Only 4 units left

Buy the Beckhoff AX2526-B900 Servo Drive - a digital servo amplifier for precision control of Beckhoff servo motors. Features configurable velocity, torque, and position control modes, integrated diagnostics, and advanced current loop regulation. The Beckhoff AX2526-B900 is suited for CNC, robotics, packaging, and multi-axis motion control. Direct replacement for existing installations.

Beckhoff C6140-0030 Beckhoff

$6,895.53

Only 2 units left

PLC Direct is not an authorized distributor. We offer a broad range of in-stock products with minimal lead time.

Beckhoff EL7041-0052 Beckhoff

$1,838.53

Only 2 units left

PLC Direct is not an authorized distributor. We offer a broad range of in-stock products with minimal lead time.

Beckhoff EL4002 Beckhoff

$411.26

In stock, 13 units

EtherCAT Terminal, 2-channel analog output, voltage, 0…10 V, 12 bit

Beckhoff AX2003 Beckhoff

$3,385.28

Only 7 units left

PLC Direct is not an authorized distributor. We offer a broad range of in-stock products with minimal lead time.

Beckhoff EP6224-0002 Beckhoff

$0.00

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PLC Direct is not an authorized distributor. We offer a broad range of in-stock products with minimal lead time.

Beckhoff EPI1008-0002 Beckhoff

$1,643.58

Only 1 unit left

PLC Direct is not an authorized distributor. We offer a broad range of in-stock products with minimal lead time.

Beckhoff EL4134 Beckhoff

$663.33

In stock, 19 units

EtherCAT Terminal, 4-channel analog output, voltage, ±10 V, 16 bit

Beckhoff IL2301-B318-0000 Beckhoff

$1,661.89

Only 4 units left

PLC Direct is not an authorized distributor. We offer a broad range of in-stock products with minimal lead time.

Beckhoff AX2090-BW50-0600 Beckhoff

$667.49

Only 5 units left

Buy the Beckhoff AX2090-BW50-0600 - a genuine Beckhoff industrial automation component engineered for reliable performance in demanding manufacturing and process control environments. The Beckhoff AX2090-BW50-0600 is a direct drop-in replacement for existing installations and ships ready for integration.

Beckhoff EL2788 Beckhoff

$1,308.20

Only 3 units left

Buy the Beckhoff EL2788 Relay - an industrial relay module providing signal switching, isolation, or safety interlock functions. Features reliable contact operation, LED indication, and standard mounting. The Beckhoff EL2788 is a direct replacement for existing relay installations.

Beckhoff KL6031 Beckhoff

$216.47

In stock, 17 units

Bus Terminal, 1-channel communication interface, serial, RS232

Beckhoff C9900-K733 Beckhoff

$483.92

Only 5 units left

PLC Direct is not an authorized distributor. We offer a broad range of in-stock products with minimal lead time.

Beckhoff EPP1018-0002 Beckhoff

$457.08

In stock, 12 units

EtherCAT P Box, 8-channel digital input, 24 V DC, 10 µs, M12

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PLC I/O terminals are modular signal interface components that connect programmable logic controllers to field devices, including sensors, actuators, switches, and drives, handling digital and analog signal conversion at the edge of the control system. PLC Direct supplies PLC I/O terminals as an independent supplier, carrying surplus sealed, refurbished, and used hardware for maintenance and replacement in installed automation systems.

Where Are PLC I/O Terminals Used in Industrial Environments?

PLC I/O terminals are used wherever a PLC-based control system must interface with field-level signals across a machine or process, from individual digital inputs and outputs to analog measurement and control channels. These components are installed in control panels, field cabinets, and distributed I/O stations throughout manufacturing and process facilities.

Facilities and operations that depend on PLC I/O terminals include:

Discrete manufacturing plants distributing I/O across machine control panels and field junction boxes connected to a central controller over EtherCAT or PROFIBUS.
Packaging and material handling operations using modular I/O terminals to handle high channel-count discrete signal requirements across conveyor and sorting systems.
Automotive assembly facilities with distributed I/O terminal racks positioned at each workstation along the production line.
Water and wastewater treatment plants connecting pump station sensors and actuators to remote I/O terminal nodes across distributed control architectures.
Chemical and process industry facilities managing analog input and output channels for flow, pressure, temperature, and level instrumentation at field cabinets.

Replacement PLC I/O terminals are among the most routinely sourced automation components, as individual terminal failures in high-cycle applications are a common maintenance event.

Which Brands of PLC I/O Terminals Does PLC Direct Stock?

PLC Direct stocks PLC I/O terminals across the major modular I/O platforms deployed in installed automation systems worldwide.

Beckhoff EtherCAT Terminals (ELxxxx series) and Bus Terminals (KLxxxx series): Digital input, digital output, analog, and TwinSAFE-rated EtherCAT terminals across the EL series, alongside KL series Bus Terminals for fieldbus-neutral I/O installations, confirmed across multiple variants including EL1809, EL2622, EL1904, and EL2904.
Siemens SIMATIC ET 200SP I/O modules: Distributed I/O modules for the ET 200SP station, covering digital and analog signal types and interfacing with PROFINET and PROFIBUS networks via IM 155-6 interface modules confirmed in stock.
Omron CJ Series I/O modules: CJ1W-ID211 digital input, CJ1W-OC211 digital output, and CJ1W-MAD42 analog I/O modules for CJ Series PLC systems, providing modular signal expansion within installed Omron control architectures.
ABB S500 I/O modules: DA501 and DA502 digital/analog combination modules and TU515/TU516 terminal units for AC500-based distributed I/O installations, supporting digital and analog signal handling across multiple channel configurations.

PLC Direct carries PLC I/O terminals as surplus sealed, refurbished, and used hardware, giving maintenance teams options across condition grades and budget requirements.

What Should You Know Before Ordering PLC I/O Terminals?

Hardware condition options: PLC Direct supplies PLC I/O terminals in surplus sealed, refurbished, and used condition. Surplus sealed units are factory-sealed stock that has not been previously installed; refurbished terminals have been inspected and tested to confirm operational functionality; used hardware is sourced from decommissioned systems and suits facilities managing lifecycle replacements under budget constraints.

Compatibility and part identification: PLC I/O terminals are platform-specific and must be matched to the correct coupler, bus controller, or interface module for the installed system. Beckhoff EL series EtherCAT terminals require an EtherCAT coupler or compatible CX controller; Siemens ET 200SP modules require an IM 155-6 interface module matched to the network protocol in use. Confirm the terminal part number, signal type, channel count, and coupler compatibility from the installed system's hardware documentation before ordering.

Warranty: All PLC I/O terminal hardware purchased from PLC Direct carries a standard 1-year PLC Direct warranty covering defects and functionality, applicable to surplus sealed, refurbished, and used products.

PLC Direct supplies PLC I/O terminal hardware for replacement and maintenance purposes and does not provide system design, programming, or integration services.

Frequently Asked Questions

Local I/O terminals are mounted directly in the PLC rack and communicate with the CPU over the backplane bus, offering the lowest latency and simplest wiring for signals close to the controller. Distributed I/O terminals are installed in remote field cabinets and communicate with the controller over a fieldbus or industrial Ethernet network such as EtherCAT, PROFIBUS, or EtherNet/IP, reducing long cable runs across large facilities or machines.

EtherCAT terminals process I/O data in a single network frame that passes through each terminal in sequence, achieving sub-millisecond cycle times without a dedicated fieldbus controller at each node. This architecture allows large numbers of terminals to be added to a station without adding network overhead, making EtherCAT terminal systems particularly suited to high-channel-count and motion-critical applications.

Modular I/O terminal ranges typically cover 24 VDC digital input and output in various channel counts, analog input and output for 4-20 mA and 0-10 V signals, thermocouple and RTD temperature measurement inputs, pulse and encoder inputs for motion feedback, and safety-rated digital I/O for SIL-rated applications. The specific signal types available depend on the platform, with Beckhoff EL series and Siemens ET 200SP both offering broad signal coverage across these categories.

On platforms that support hot-swap capability, individual terminals can be replaced while the station remains powered and the network stays active, with the controller detecting the module change and resuming communication after reinsertion. Beckhoff EL series terminals and Siemens ET 200SP modules with multi-hot-swap support both offer this capability, though the specific behavior depends on the interface module and controller configuration in the installed system.

Most PLC I/O terminals have per-channel and module-level status LEDs that indicate signal state and fault conditions, and the controller's diagnostic buffer will typically log the specific module address and fault type when a terminal fails or goes offline. Cross-referencing the module address in the hardware configuration with the physical terminal position in the cabinet yields the part number needed to source a replacement.