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Beckhoff CX8091

The Beckhoff CX8091 is a control system with a switched Ethernet port and a bus interface for E-bus or K-bus terminals. It automatically recognizes the connected I/O system during start-up and is programmed with TwinCAT 2 through the fieldbus interface or the additional Ethernet interface. It supports BACnet or OPC UA, with simultaneous use not recommended due to the small memory.

Source checked10/10 values · 2026-10-25Beckhoff AutomationPLC
CX8091X1X2X33 × ETHERNETArm9™, 400 MHz24 V DC (-15%/+20%)IP20CX8091 · FRONTSchematic · port count from spec
IP rating
IP20
Weight
0.18kg

Specification

1 source
Categoryplc
Ethernet ports3
ProcessorArm9™, 400 MHz
Supply voltage24 V DC (-15%/+20%)
Power consumption0.003 kW
Operating temp min0 °C
Operating temp max55 °C

Quick answers

How much does the Beckhoff CX8091 weigh?
0.18 kg, per Embedded PC with Arm9™ and BACnet/IP or OPC UA (beckhoff.com).
What is the IP rating of the Beckhoff CX8091?
IP20, per Embedded PC with Arm9™ and BACnet/IP or OPC UA (beckhoff.com).

Study notes

  • Product status: regular delivery, not recommended for new projects; recommended alternative is CX8290.
  • BACnet is supported as an alternative protocol to OPC UA; simultaneous use is not recommended due to the small memory.
  • I/O connection accepts E-bus or K-bus terminals and automatically recognizes the connected I/O system during start-up.
  • Programming languages: IEC 61131-3; control software: TwinCAT 2 PLC.
  • Main memory: 64 MB DDR2 RAM, not expandable. Flash memory: microSD slot with 512 MB card included, optionally expandable.
  • Integrated 1-second UPS with 1 MB on microSD card.
  • Interfaces: 1 x RJ45 10/100 Mbit/s, 1 x USB device behind the front flap, 1 x bus interface; the bus interface has 2 x RJ45 switched at 100 Mbit/s.
  • Cooling is passive; diagnostics LEDs are 1 x TC status, 1 x WD and 1 x error.
  • Internal battery-backed clock for time and date; battery behind the front flap and exchangeable.
  • Current supply for E-bus/K-bus: 2 A. Max power consumption for E-bus/K-bus: 10 W (5 V/max. 2 A).
  • Dimensions: 64 mm x 100 mm x 73 mm. Relative humidity: 95%, no condensation. Storage temperature: -25…+85°C.
  • Vibration/shock resistance conforms to EN 60068-2-6/EN 60068-2-27; EMC immunity/emission conforms to EN 61000-6-2/EN 61000-6-4.

Safety

  • Approvals/markings: CE, UL, ATEX, IECEx, cFMus.
  • ATEX marking: II 3G Ex nA IIC T4 Gc; II 3D Ex tc IIIC T135°C Dc.
  • IECEx marking: Ex nA IIC T4 Gc; Ex tc IIIC T135°C Dc.
  • cFMus marking: Class I, Division 2, Groups A, B, C, D; Class I, Zone 2, AEx ec IIC T4 Gc.
  • Windows Embedded CE 6 extended support has ended; up-to-date security updates can no longer be provided.
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