I/O refers to Input/Output, which is the transfer of data between the CPU and a peripheral device. I/O modules, which can be digital and analog, are self-contained components that interact between the CPU and peripherals.
Axis 03504-001 digital/analogue I/O module

Axis 03504-001 digital/analogue I/O module

Axis
£743.99
Axis D3110 Mk II digital/analogue I/O module Analog Relay channel

Axis D3110 Mk II digital/analogue I/O module Analog Relay channel

Axis
£520.99
Axis 02861-001 digital/analogue I/O module Relay channel

Axis 02861-001 digital/analogue I/O module Relay channel

Axis
£371.99
Axis 02554-001 digital/analogue I/O module

Axis 02554-001 digital/analogue I/O module

Axis
£203.99
Axis 02553-001 digital/analogue I/O module

Axis 02553-001 digital/analogue I/O module

Axis
£149.99
ATEN 8-Channel Relay Expansion Box

ATEN 8-Channel Relay Expansion Box

Aten
£306.99
ATEN 8-Channel Digital I/O Expansion Box

ATEN 8-Channel Digital I/O Expansion Box

Aten
£306.99
APC Smart-UPS SRT Output Hardwire Kit, 5kVA

APC Smart-UPS SRT Output Hardwire Kit, 5kVA

APC
£278.99
Axis 0821-001 digital/analogue I/O module Relay channel

Axis 0821-001 digital/analogue I/O module Relay channel

Axis
£324.99