Serial Remote I/O Modules for RS-232, RS-422, and RS-485 Networks

Serial Remote I/O modules provide reliable signal acquisition and control via RS-232, RS-422, or RS-485 interfaces. These modules offer dependable connectivity for legacy and modern industrial systems alike, especially useful if you're handling sensor inputs, relay outputs, voltage readings or TTL signals.

Contact our team for advice on selecting the right Serial I/O module for your specific application.

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Serial Remote I/O Modules

Showing 73 of 73 Serial Remote I/O Modules items

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420S-OEM
Sealevel 420S-OEM
RS-232 Modbus RTU to 16 Isolated Digital Input/8 Form C Relay Output OEM Board
£254.50
420M
Sealevel 420M
RS-485 Modbus RTU to 16 Isolated Digital Input/8 Form C Relay Output Adapter
£266.50
420M-OEM
Sealevel 420M-OEM
RS-485 Modbus RTU to 16 Isolated Digital Input/8 Form C Relay Output OEM Board
£254.50
410S
Sealevel 410S
RS-232 Modbus RTU to 16 Isolated Digital Input/16 Reed Relay Output Adapter
£254.50
410S-OEM
Sealevel 410S-OEM
RS-232 Modbus RTU to 16 Isolated Digital Input/16 Reed Relay Output OEM Board
£242.00
410M
Sealevel 410M
RS-485 Modbus RTU to 16 Isolated Digital Input/16 Reed Relay Output Adapter
£254.50
410M-OEM
Sealevel 410M-OEM
RS-485 Modbus RTU to 16 Isolated Digital Input/16 Reed Relay Output OEM Board
£242.00
570S
Sealevel 570S
RS-232 Modbus RTU to 8 x 16-bit Analog Input – 8 Isolated Digital Input/8 Form C Relay Output Adapter
£403.00
570M
Sealevel 570M
RS-485 Modbus RTU to 8 Analog Input – 8 Isolated Digital Input/8 Form C Relay Output Adapter
£403.00
540S
Sealevel 540S
RS-232 Modbus RTU to 32 Open-Collector Output Adapter
£378.00
540S-OEM
Sealevel 540S-OEM
RS-232 Modbus RTU to 32 Open-Collector Output OEM Board
£366.00
540M
Sealevel 540M
RS-485 Modbus RTU to 32 Open-Collector Output Adapter
£378.00
540M-OEM
Sealevel 540M-OEM
RS-485 Modbus RTU to 32 Open-Collector Output OEM Board
£366.00
Why Use Serial I/O When Ethernet Is Available?
Serial modules are simpler and often more predictable in environments with electrical noise. They suit applications where deterministic communication and minimal overhead matter more than bandwidth.

What Should You Consider for RS-485 Systems?
Check the maximum number of nodes per bus and whether termination resistors are built-in. Correct line balancing is key to keeping communication stable over long runs.

How Do They Fit into Mixed Networks?
Many serial I/O modules can be paired with protocol gateways, extending the life of older installations by linking them to modern supervisory systems.