PLC I/O Terminals

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$1,526.84

Only 3 units left

Buy the Beckhoff KL3351-0000 - a genuine Beckhoff industrial automation component engineered for reliable performance in demanding manufacturing and process control environments. The Beckhoff KL3351-0000 is a direct drop-in replacement for existing installations and ships ready for integration.

Beckhoff EL6731-1006 Beckhoff

$0.00

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Buy the Beckhoff EL6731-1006 - a genuine Beckhoff industrial automation component engineered for reliable performance in demanding manufacturing and process control environments. The Beckhoff EL6731-1006 is a direct drop-in replacement for existing installations and ships ready for integration.

Beckhoff EL3144 Beckhoff

$709.17

Only 6 units left

EtherCAT Terminal, 4-channel analog input, current, 0…20 mA, 16 bit, single-ended

Beckhoff KL4414 Beckhoff

$477.74

Only 3 units left

Buy the Beckhoff KL4414 - a genuine Beckhoff industrial automation component engineered for reliable performance in demanding manufacturing and process control environments. The Beckhoff KL4414 is a direct drop-in replacement for existing installations and ships ready for integration.

Beckhoff C9900-U320 Beckhoff

$825.00

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 AX2503-B750 Beckhoff

$2,842.00

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 EP3184-1002 Beckhoff

$702.96

Only 8 units left

Buy the Beckhoff EP3184-1002 - a genuine Beckhoff industrial automation component engineered for reliable performance in demanding manufacturing and process control environments. The Beckhoff EP3184-1002 is a direct drop-in replacement for existing installations and ships ready for integration.

Beckhoff C6515-0040 Beckhoff

$2,294.06

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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 C9900-A160-2 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 AX2090-B900 Beckhoff

$2,685.52

Only 7 units left

Buy the Beckhoff AX2090-B900 - a genuine Beckhoff industrial automation component engineered for reliable performance in demanding manufacturing and process control environments. The Beckhoff AX2090-B900 is a direct drop-in replacement for existing installations and ships ready for integration.

Beckhoff AX2503-B750-0000 Beckhoff

$2,219.45

Only 3 units left

Buy the Beckhoff AX2503-B750-0000 - a genuine Beckhoff industrial automation component engineered for reliable performance in demanding manufacturing and process control environments. The Beckhoff AX2503-B750-0000 is a direct drop-in replacement for existing installations and ships ready for integration.

Beckhoff EL3204-0200 Beckhoff

$1,845.24

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 C6525-1022-0050 Beckhoff

$1,177.64

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 EJ1918 Beckhoff

$634.20

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 FC7501 Beckhoff

$1,174.70

Only 6 units left

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

Beckhoff C6640-0030 Beckhoff

$4,345.20

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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 EP9224-0037 Beckhoff

$1,260.41

Only 8 units left

Buy the Beckhoff EP9224-0037 - a genuine Beckhoff industrial automation component engineered for reliable performance in demanding manufacturing and process control environments. The Beckhoff EP9224-0037 is a direct drop-in replacement for existing installations and ships ready for integration.

Beckhoff C6650-0040 Beckhoff

$2,659.80

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 EP1312-0001 Beckhoff

$650.07

Only 3 units left

Buy the Beckhoff EP1312-0001 - a genuine Beckhoff industrial automation component engineered for reliable performance in demanding manufacturing and process control environments. The Beckhoff EP1312-0001 is a direct drop-in replacement for existing installations and ships ready for integration.

Beckhoff KL5151-0050 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 EL3002 Beckhoff

$502.92

In stock, 19 units

EtherCAT Terminal, 2-channel analog input, voltage, ±10 V, 12 bit, single-ended

Beckhoff IL2301-B900 Beckhoff

$367.50

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 C6030-0070 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 EL3202-0020 Beckhoff

$655.49

Only 7 units left

Buy the Beckhoff EL3202-0020 Terminal/Connector - an industrial wiring component providing reliable electrical connections in control panels. Features robust construction, easy installation, and standard mounting. The Beckhoff EL3202-0020 is a direct replacement for existing installations.

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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.