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