In the field of industrial automation, embedded controllers need to provide powerful computing power, flexible I/O expansion, and reliable data retention capabilities within a compact size. The CX5010 and CX5020 series embedded PCs launched by Beckhoff are designed specifically for this purpose. They adopt DIN rail installation, fanless design, can directly connect to Beckhoff Bus Terminals (K-bus) or EtherCAT Terminals (E-bus), and combine TwinCAT automation software with Windows CE or Windows Embedded Standard operating systems to become a powerful PLC and motion control system. Among them, CX5010 is equipped with Intel Atom Z510 processor (1.1 GHz), CX5020 is equipped with Atom Z530 processor (1.6 GHz), both of which are equipped with 512 MB RAM (CX5020 can choose 1 GB) and 128 MB Compact Flash card (expandable). This article will comprehensively analyze the system composition, installation specifications, interface configuration, 1-second UPS persistent variable mechanism, BIOS settings, status diagnosis, and common troubleshooting of CX50x0 from the perspective of engineering applications, providing a detailed technical reference for on-site engineers.
System Overview and Model Differences
CX5010 and CX5020 belong to the CX5000 series, and their core design concepts are modularity and scalability. The basic CPU module itself includes two independent Gigabit Ethernet ports (10/100/1000 Mbit/s), four USB 2.0 interfaces, a DVI – D interface, and an internal bus interface (K-bus or E-bus, depending on the ordered model) for connecting to Beckhoff bus terminals. In addition, users can add RS232, RS422/RS485, PROFIBUS master/slave, CANopen master/slave, PROFINET RT controller/device or EtherCAT slave functions through the option interfaces on the right (CX50x0 N030/N031/M310/B310/M510/B510/M930/B930/B100, etc.).
Main technical differences:
Features CX5010 CX5020
Processor Intel Atom Z510 1.1 GHz Intel Atom Z530 1.6 GHz
Memory 512 MB RAM (non expandable) 512 MB RAM (optional 1 GB factory pre installed)
Maximum power consumption of 12 W and 12.5 W
Other specifications are the same (interface, size, temperature range, etc.)
Both have external dimensions of 100 mm × 106 mm × 92 mm (height × width × depth), a weight of approximately 575 g, a working temperature of -25 ° C~+60 ° C, a storage temperature of -40 ° C~+85 ° C, a protection level of IP20, and comply with EN 61000-6-2/6-4 electromagnetic compatibility standards.
Mechanical installation and heat dissipation requirements
The CX50x0 series is designed specifically for DIN rail (top cap rail) installation. The correct installation direction and ventilation gap are crucial for ensuring stable operation of the CPU at an ambient temperature of 60 ° C.
2.1 Installation direction
The top and bottom of the equipment casing are equipped with ventilation holes. Therefore, the CX50x0 must be installed horizontally on the guide rail (with the interface facing the side and the ventilation holes vertically up and down). Vertical installation (such as standing the device upright) or side installation is strictly prohibited, otherwise it may cause insufficient CPU heat dissipation, overheating, frequency reduction, or system instability.
2.2 Ventilation gap
At least 30mm of free space should be reserved above and below the equipment combination to ensure natural convection of cold air. If multiple power modules or bus terminals are installed on the guide rail, it should also be ensured that there is sufficient air flow around the entire component.
2.3 Installation steps
Place the orange DIN rail lock on the back of the device in the open position.
Insert the device into the guide rail from top to bottom and hear a "click" sound to indicate that the right side is locked.
Use a screwdriver to push up the orange lock on the left side until it fully clicks into the guide rail.
Check if the equipment is securely fixed.
When disassembling, first unplug the power supply and all data cables, then pull down the orange lock buckle to remove the device from the guide rail.
Power connection and grounding
3.1 Power Supply Requirements
The power module of CX50x0 is located on the left (or right, depending on the configuration) side of the CPU module and is connected to 24 V DC through the upper spring terminal. Power requirements:
Rated voltage: 24 V DC (allowable range -15%/+20%, approximately 20.4 V~28.8 V)
Maximum current: The sum of CPU module and all bus terminals must not exceed 4 A
Wire cross-section: 0.5~2.5 mm ² (AWG 20~14)
Stripping length: 8-9 mm
UL compliance requirements: For UL certification, CX controllers must be powered by a 24 V power supply that complies with NEC Class 2 and is protected by a fuse with a rated current not exceeding 4 A (compliant with UL 248). Class 2 power supplies shall not be connected in series or parallel with other Class 2 power supplies.
3.2 Terminal Definition and Grounding
The power terminal block is marked with:
24 V: Positive pole
0 V: Negative pole
PE: Protective Grounding (Power Contact)
Important grounding rules:
The PE contact must be at the same potential as 0 V (connected inside the control cabinet).
The requirements of EN 60204-1:2006 regarding PELV circuits must be followed: one side of the circuit (or a point of the power supply) must be connected to the protective grounding system.
If the power supply is disconnected, the 24V line should be disconnected first, followed by the 0V line, otherwise a current loop may be formed through the shielding layer.
The connected external devices (such as the control panel) must have the same PE and GND potential as the CX unit, otherwise it may damage the equipment.
3.3 Power LED indicator light
There are two sets of LEDs on the power module:
Us 24V (green): CPU module power supply is normal
Up 24V (green): Bus terminal power supply is normal
K-BUS RUN (green): K-bus communication is normal
K-BUS ERR (flashing red): K-bus error (see diagnostic section for details)
In E-bus mode, the L/A LED (green, indicating connection/activity) will be displayed.

Interface Explanation
4.1 Ethernet ports (X000, X001)
Two independent Gigabit RJ45 ports. Port 1 (X000) is usually used as an IT network port, while Port 2 (X001) is configured as an EtherCAT communication port at the factory. Both ports support 10/100/1000 Mbit/s. LED indication:
Upper LED (yellow): constantly on=connected to the network, flashing=data transmission and reception
Lower LED: Green=10/100 Mbit, Red=1000 Mbit (Gigabit)
Note: Unlike CX1020, CX50x0 does not have an integrated switch internally. To achieve a linear topology, an external switch is required.
4.2 USB interface (X100~X103)
Four USB 2.0 Type A interfaces, each with a maximum power supply of 500 mA. Can be used to connect keyboards, mice, USB drives, touch screens, etc. If larger current peripherals are required, an active USB hub should be used.
4.3 DVI – D interface (X200)
Digital video output, supporting a maximum resolution of 2560 × 1440. VGA signal is not supported, therefore DVI to VGA passive adapter cannot be used (unless an active conversion box is used). It is recommended that the length of DVI cable should not exceed 5 meters, otherwise signal attenuation may cause abnormal display.
4.4 Serial interface (optional)
CX50x0‑N030:RS232, 9-pin D-SUB male head, maximum baud rate 115.2 kbit. Pin allocation conforms to standard PC COM ports.
CX50x0‑N031:RS422/RS485, 9-needle D-SUB female head. RS485 mode is half duplex, with no feedback and terminal resistance enabled (default configuration); RS422 is full duplex, with echo enabled and terminal resistor enabled. Pin 2/3 is data+, 7/8 is data -, 5 is GND, and 6 provides+5 V (100 mA).
4.5 Optional fieldbus interface
The following single channel interfaces can be added through factory pre installed options (only one can be used at a time):
PROFIBUS master/slave (M310/B310)
CANopen Master/Slave (M510/B510)
PROFINET RT controller/device (M930/B930, dual RJ45 switch)
EtherCAT slave (B100, dual RJ45)
If multiple fieldbus interfaces are required, they can be extended through EtherCAT terminals (such as EL6731 PROFIBUS master station).
CF card and storage medium
5.1 CF card slot
There is a Compact Flash card slot at the front of the device, which uses a push push ejection mechanism: gently push the card to eject it by about 4 mm to remove it; Push it all the way when inserting, and the card will be about 1 mm lower than the housing. CF card is a memory interface, not an I/O type CF card.
Important: Replacing the CF card must be done when the device is powered off, otherwise it may cause system crashes or data damage.
5.2 CF card selection and lifespan
Beckhoff strongly recommends using only its industrial grade CF cards (extended temperature range to+85 ° C, with higher read and write life). Ordinary commercial CF cards are prone to bad blocks or data loss in industrial environments.
Optional capacities: 128 MB (standard), 1 GB, 2 GB, 4 GB, 8 GB, 16 GB. If you need Windows Embedded Standard 2009, the CF card capacity needs to be at least 2 GB; if you use Windows Embedded Standard 7 P (32-bit), you need CX5020 with 1 GB RAM and 8 GB CF card.
The expected replacement cycle for CF cards is 10 years (recommended by Beckhoff).
1-second UPS and persistent variable protection
The CX50x0 is equipped with a capacitive 1-second UPS (UltraCap). When the main power supply is cut off, the UPS can provide brief power to the CPU (new devices can support several seconds, at least 1 second throughout their lifespan), allowing the system to save persistent variables (PERSISTENT) to the CF card. After the power is restored, these variables will automatically reload, achieving seamless recovery after a power outage.
6.1 Working principle
During normal power supply, the UPS capacitor is in a charging state. After power failure, the function block FB_S-UPS in TwinCAT will detect power failure and perform operations according to the preset mode. The default mode is eSUPs_WrPersistData_Shutdown: first save persistent data, and then perform Quick Shutdown.
Data storage location:
TwinCAT 2: TwinCAT Boot TCLC_Tx.wbp (x is the runtime system number)
TwinCAT 3:TwinCAT3.1BootPort_85x.bootdata
6.2 BIOS Settings
Enter BIOS → PC Health Status:
SUSV: Enable/Disable 1-second UPS (must be set to [Enabled])
SUSV holds USB: Does the USB port maintain power supply during UPS activation (for external storage backup)
SUSV Status: Display the current capacitance percentage and charging/discharging status
6.3 FB_S-UPS Function Block Configuration
In TwinCAT PLC, it is necessary to cyclically call FB_S-UPS. Key input parameters:
eUPSMode:
ESUPs_WrPersistData_Shutdown (default): Automatically shuts down after saving persistent data
ESUPs_WrPersistData_CoShutdown: Only saves data, does not shut down
ESUP_SimediateShutdown: Immediately shut down (without saving data)
ESUPS-CheckPowerStatus: Only detects power status
TRecoverTime: The waiting time for recovery after a brief power outage (default 10 seconds)
To ensure sufficient time to write data, it is recommended to stop calling other application logic after detecting a power failure:
text
IF NOT FB_S_UPS.bPowerFailDetect THEN
//Call normal program
END_IF
6.4 Windows Write Filter Attention
If the system has enabled Windows write filters (EWF/FBWF/UWF), the path for saving persistent data must be in the exception list. By default, the Boot directory is already in the FBWF exception list. If persistent data cannot be saved, please check the write filter configuration.
6.5 Verify persistent data loading status
In TwinCAT 2, the following can be checked using SystemInfotype.bootFatages:
Bit 4=1: Persistent variable loaded (no errors)
Bit 5=1: Invalid persistent variable (backup copy loaded)
In TwinCAT 3, PlcAppSystemInfo. BootDataLoaded and PlcAppSystemInfo. OldBootData are used.
If you want to clear invalid persistent data backups every time you start, you can set the following in the registry:
text
[HKEY_LOCAL_MACHINESOFTWAREBeckhoffTwinCATPLC]
"ClearInvalidPersistentData"=dword:00000001

Key points of BIOS settings
The CX50x0 is pre configured at the factory and it is generally not recommended for users to modify the BIOS. But in certain special circumstances (such as adjusting the boot sequence, enabling virtualization technology, etc.), changes can be made by entering the BIOS. Here are a few key options:
Standard CMOS Features: Set date, time, and hard disk parameters. Note that the CF card is recognized as an IDE Primary Master.
Advanced BIOS Features:
Quick Power On Self Test: Enabling it can speed up startup.
First/Second Boot Device: Set the boot sequence (usually Hard Disk).
Full Screen Logo: The startup logo can be disabled to view POST information.
CPU Feature → Virtualization Technology: If you need to run a virtual machine, it can be enabled, but it will slightly affect real-time performance.
Integrated Peripherals → Onboard Device → Onboard Lan Controller: Two network ports are enabled by default and cannot be turned off.
Power Management Setup: The Power Supply Type must remain in [AT] mode (ATX mode is not applicable).
PC Health Status: View system temperature, voltage, battery voltage, and SUSV status.
Warning: Under Windows CE system, it is strictly prohibited to modify BIOS, otherwise it may cause the operating system to fail to start.
Status LED and Fault Diagnosis
8.1 CPU module LED
Meaning of LED color
PWR green power supply is normal
TC Green TwinCAT Operation Mode
TC Red TwinCAT Stop Mode
TC Blue TwinCAT Configuration Mode
HDD red flashing CF card read/write activity
FB1/FB2 depends on the fieldbus and is defined by options
8.2 K-bus Error Diagnosis
When the red K-BUS ERR LED on the power module flashes, it indicates a fault in the bus terminal configuration or communication. The error code is read out through a flashing sequence:
Rapid continuous flashing: Error code begins
Slow flashing (N times): Error code
Second slow flashing (M times): incorrect parameter
Common errors:
3 slow flashes (parameter 0): K-bus command error. Possible reasons: No terminals have been inserted, or one terminal is damaged. The "splitting method" can be used to remove half of the terminals and observe whether the error disappears to locate the faulty terminal.
4 slow flashes (parameter 0 or n): K-bus data interruption. If the parameter is 0, it means that the power module is immediately disconnected and it is necessary to check whether the bus terminal (KL9010/EL9010) is installed. If the parameter is n, it means that the wire is disconnected after terminal n. Check if terminal n+1 is connected correctly.
5 slow flashes: Register communication error, terminal at position n needs to be replaced.
7 slow flashes: Process data length does not match, check if the configuration matches the actual terminal.
In K-bus mode, the system status byte can be read through TwinCAT. If the status byte ≠ 0, there may be synchronization issues. Suggest setting the PLC task cycle to less than 50 ms (K-bus update typical value is 1-5 ms).
Common troubleshooting
Possible causes and solutions for the fault phenomenon
After power on, there is no response. The power supply is not connected, the fuse is blown, and the polarity is reversed. The power supply terminal measures the voltage between 24V and 0V; Check the external fuse; Confirm correct wiring
The device cannot fully boot due to CF card damage, BIOS settings errors, file system corruption. Try reformatting the CF card and restoring the image; Load BIOS default settings; Contact Beckhoff
After startup, TwinCAT cannot connect or control abnormal software configuration errors, terminal configuration changes, and network issues. Check TwinCAT routing settings; Rescan terminal configuration; Check EtherCAT cable
K-BUS ERR continuous flashing terminal damage, poor contact, and missing end terminal. Locate the faulty terminal according to the flashing code mentioned above; Re plug and unplug the terminals; Install KL9010
Persistent data failure after power outage, UPS not enabled, write filter blocked, data exceeding 1 MB, check if SUSV is enabled in BIOS; Check FBWF exceptions; Reduce the size of persistent variables
USB devices cannot recognize insufficient power supply (>500 mA), driver issues using an active USB hub; Install the corresponding driver program
Maintenance and retirement
10.1 Regular replacement of components
Motherboard battery (CR2032): Replace every 5 years to maintain RTC and BIOS settings. When replacing, pay attention to the positive pole facing outward, and the model must be Panasonic CR2032 (3 V/225 mAh).
CF card: It is recommended to replace it every 10 years (industrial grade). Before replacement, the system image should be backed up first.
System fan: CX50x0 is designed without a fan and does not require replacement.
10.2 Retirement and Disposal
When disassembling, first disconnect the power supply, then release the DIN rail lock and remove the entire module assembly from the rail. If necessary, the CF card can be removed and physically destroyed to prevent data leakage. Electronic components should be disposed of in accordance with national regulations on electronic waste.
