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Protocol Converters

Protocol converters are standalone devices that translate communication signals between two incompatible industrial protocols, enabling field instruments, serial PLCs, drives, and remote terminals that cannot share a native protocol to exchange data across a common network. PLC Direct stocks Red Lion protocol converters across various product families, available as surplus sealed, refurbished, and used hardware. Contact PLC Direct to confirm availability.

Where are Protocol Converters used in industrial environments?

Protocol converters are deployed wherever a field device or controller uses a communication protocol that the host network, SCADA system, or upstream PLC cannot natively read, requiring hardware-level translation before data exchange can occur. They are a standard component in legacy system retrofits, multi-vendor machine integrations, and any facility where serial field devices must remain in service alongside modern Ethernet-based control infrastructure.

Facilities and operations that depend on protocol converters include:

Manufacturing plants integrating legacy RS-232 or RS-485 serial instruments with EtherNet/IP or PROFINET controllers, where replacing the serial devices is not economically justifiable during an ongoing production upgrade.

Oil and gas facilities bridging isolated Modbus RTU field transmitters and remote terminal units into centralized TCP/IP-based SCADA and historian platforms across extended pipeline or processing networks.

Water and wastewater utilities connecting serial Modbus RTU outstations to Ethernet SCADA systems, managing distributed pump stations and treatment processes across geographically separated sites.

OEM machine builders standardizing communication between third-party serial components, such as barcode readers, weighing systems, or legacy drives, and a fixed EtherNet/IP or Modbus TCP/IP control platform.

Packaging and material handling operations where individual serial-protocol drives or sensors on existing lines must report data to a newer Ethernet-based MES or supervisory system without line stoppage for re-wiring.

A failed protocol converter isolates every device on the affected serial segment from the control network, making exact part number, protocol pairing, and port configuration matching essential before ordering a replacement.

Which brands of Protocol Converters does PLC Direct stock?

Red Lion hardware comprises three product families.

Red Lion C48 Series: Compact DIN-rail protocol converters where the model suffix identifies the specific conversion type; confirm the complete part number against the installed unit before ordering, as different C48 variants are configured for different signal and protocol combinations.

Red Lion CR Series: Configurable multi-port data station units, including the CR1000 and CR3000, programmed via Red Lion's Crimson software to perform simultaneous protocol conversion across serial, Ethernet, and fieldbus connections within a single device.

Red Lion CSTC Series: Serial-to-Ethernet terminal servers, including the CSTC8000 and the isolated CSTC8ISO, that present legacy RS-232 or RS-485 serial devices as TCP/IP-accessible nodes on an industrial Ethernet network.

PLC Direct stocks Red Lion protocol converters as surplus sealed, refurbished, and used hardware, depending on available inventory.

What should you know before ordering Protocol Converters?

Hardware condition options: Surplus sealed units are unused and in original manufacturer packaging. Refurbished units have been inspected and restored to functional operating condition. Used units are tested and operational, with conditions stated on each product listing.

Compatibility and part identification: Protocol converters must be matched by exact part number. Within the Red Lion C48 family, the model suffix encodes the specific protocol conversion the unit performs, meaning a physically similar unit with a different suffix will not replicate the original function. For CR Series data stations, the model number also determines the number of serial ports and available interface types, both of which affect compatibility with the installed wiring and connected devices.

Warranty: All protocol converter hardware purchased from PLC Direct carries a standard 1-year warranty covering defects and functionality, applicable to surplus sealed, refurbished, and used products. PLC Direct supplies protocol converter hardware for replacement and maintenance purposes and does not provide system design, programming, or integration services.

Frequently asked questions

A standalone protocol converter, such as a Red Lion C48 or CSTC unit, mounts on a DIN rail and bridges protocols through external serial or Ethernet ports, independent of any controller chassis. An in-rack communication module installs directly into a PLC backplane and exchanges data with the host processor at the backplane level. Protocol converters are controller-agnostic and can serve devices across multiple controller platforms; in-rack modules are tied to a specific PLC family and chassis.

The complete part number is the minimum requirement; the installed unit's label is the most reliable source. If the label is damaged or missing, the original panel drawings, wiring diagrams, or commissioning documentation should identify the model. For Red Lion CR Series units, also note the firmware version if visible, as some Crimson-configured installations have version dependencies that affect compatibility with a replacement unit.

A surplus sealed unit will contain no configuration; the protocol mapping, port settings, and any Crimson software parameters must be loaded before the unit can be placed into service. A refurbished or used unit may retain a prior installation's configuration in non-volatile memory, which must be cleared and reconfigured before deployment. Having a backup of the original configuration file or sufficient documentation to recreate it is strongly advisable before ordering any replacement.

On fixed-function C48 models, the protocol conversion is determined by the hardware and cannot be changed through software. On CR Series data stations, Crimson software allows the protocol mapping to be modified, but the available options are constrained by the physical interfaces supported by the unit. If the application requirements have changed, verify that the existing unit's hardware interfaces are compatible with the new protocol pair before ordering a replacement or attempting reconfiguration.

Used and refurbished units may retain a prior installation's configuration in non-volatile memory, including port settings, baud rates, and protocol parameters that do not match the new application. Before installation, clear any existing configuration and verify the firmware version against the requirements of the connected controller and field devices, as certain Red Lion CR Series firmware revisions have known compatibility constraints with specific Crimson software versions. If the replacement unit cannot be bench-tested before being installed in the panel, having the correct configuration file ready to load immediately after power-up will reduce commissioning time and avoid unplanned downtime.