# Beckhoff CX8191

Hardware · `CX8191` · verification: source checked

The Beckhoff CX8191 is a control system with an Arm Cortex-A9 processor and TwinCAT 3 runtime. It connects to E-bus or K-bus I/O terminals and has a switched Ethernet bus interface. It supports BACnet for building automation and can also use OPC UA, MQTT, and Modbus TCP.

## Specification

| Property | Value |
|---|---|
| Category | embedded pc |
| Weight | 0.23 kg |
| Ethernet ports | 3 |
| Processor | Arm® Cortex®-A9, 800 MHz |
| Supply voltage | 24 V DC (-15%/+20%) |
| Power consumption | 0.004 kW |
| IP rating | IP20 |
| Operating temp min | -25 °C |
| Operating temp max | 60 °C |

## Connected

- Manufacturer: [Beckhoff Automation](https://machineschema.com/manufacturer/beckhoff.md)
- Protocols: [MQTT](https://machineschema.com/protocol/mqtt.md), [Modbus TCP](https://machineschema.com/protocol/modbus-tcp.md), [OPC UA](https://machineschema.com/protocol/opc-ua.md)

## Safety

- CE and UL approvals/markings.

## Study notes

- Supports BACnet protocol; the BACnet license is already installed on the device.
- With EL6861 BACnet-MS/TP terminals, the CX8191 can act as a router to MS/TP networks, including support for several MS/TP networks.
- Further TwinCAT 3 protocols include Modbus RTU, which has no matching protocol id in the schema.
- TwinCAT 3 platform level is Economy (20); programming is done with TwinCAT 3 via the fieldbus interface or the additional Ethernet interface.
- Operating system is Windows Embedded Compact 7; extended support has ended, security updates are no longer provided, and TwinCAT is supported only up to build 4024.
- Product status is regular delivery, not recommended for new projects; the recommended alternative is CX8290.
- I/O connection supports E-bus or K-bus terminals, with automatic recognition of the connected I/O system during start-up.
- Bus interface provides 2 x RJ45 switched ports at 100 Mbit/s; the separate Ethernet interface is 1 x RJ45 10/100 Mbit/s.
- Main memory is 512 MB DDR3 RAM (not expandable); flash memory is a microSD slot with 512 MB card included.
- Includes an integrated 1-second UPS with 1 MB on microSD card and a battery-backed clock for time and date (exchangeable battery behind front flap).
- Current supply for E-bus/K-bus is 2 A; max power consumption is 4 W, 9 W with UPS loading, and 10 W for E-bus/K-bus (5 V/max. 2 A).
- Dimensions 71 x 100 x 73 mm; storage temperature -40…+85°C; relative humidity 95% no condensation; vibration/shock conforms to EN 60068-2-6/-2-27; EMC conforms to EN 61000-6-2/-6-4.

## Sources

1. [Embedded PC with Arm® Cortex®-A9 and BACnet/IP](https://www.beckhoff.com/en-en/products/ipc/embedded-pcs/cx8100-arm-r-cortex-r-a9/cx8191.html) (accessed 2026-10-25)

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