BECKHOFF CU20xx/CU22xx Switch Installation and Troubleshooting

If the Activity light continues to flash rapidly but communication is abnormal: there may be a broadcast storm or frame conflict, check the network loop or faulty device.

If the 100/1000 light is not on but the Link light is on, it indicates that the negotiation is for 10M, which may be due to poor network cable quality or the other end only supporting 10M.

Functional principles and usage limitations

5.1 Storage and forwarding mechanism

The switch adopts a store and forward mode: after receiving a complete frame, it first checks the CRC, discards erroneous frames (CRC error), frames that are too short (<64 bytes), or frames that are too long (>1536 bytes, in the case of non jumbo frames), and then forwards them to the target port. This ensures that 'junk frames' in the network will not be spread.

5.2 Address Learning and Aging

The switch automatically learns the MAC address of the devices connected to each port and maintains an address table (>1000 addresses per port). If an address is inactive for about 5 minutes (aging time), it will be removed from the table and re learned later. This mechanism allows the switch to connect the entire network segment without affecting performance.

5.3 Throughput

CU series switches can achieve line speed forwarding (148800 frames per second @ 100M, or higher @ Gigabit), ensuring real-time data is unobstructed.

5.4 Mega frame support (proprietary to CU2208)

CU2208 supports frames of up to 9720 bytes, but please note:

Mega frames only take effect on gigabit link ports.

Mega frames require extremely high internal data throughput, with a maximum of 2 ports simultaneously transmitting mega frames at full load, otherwise frame loss may occur.

The macro frame is not standardized, and it needs to be confirmed that the frame format used by the application is compatible with CU2208.

5.5 PoE not supported

CU series switches do not comply with the IEEE 802.3 PoE standard and cannot be used as PSE (power supply equipment) or PD (power receiving equipment). Any PSE device connected to the switch (such as a PoE injector) must not apply voltage, otherwise it may damage the switch or pose a safety hazard.

Common Troubleshooting Ladder Table

Troubleshooting steps for possible causes of fault phenomena

The whole machine has no power (Power LED off). The power supply is not connected or the voltage is insufficient. Measure the voltage of the power supply terminal (18-30V); Check if the polarity is correct; Check if the external fuse is blown

The Link light on a certain port does not light up, the network cable is disconnected, the other end device is not powered on, or the port is faulty. Replace the network cable for testing; Check if the peer device is started; Try connecting to another port to confirm if the port is damaged

Link light on but unable to communicate (Ping timeout) IP address configuration error or switch not learning MAC confirmation that the peer IP is in the same subnet; Check if there is a broadcast storm (Activity light keeps flashing); Try restarting the switch

The network speed is much lower than expected due to poor cable quality, resulting in a speed drop to 10M. Check the 100/1000 LED status; Replace Cat5e or Cat6 cables; Avoid wiring that is too long (>100m)

Giant frame transmission packet loss (CU2208): More than 2 ports are simultaneously using giant frames or the link is limited to 100Mbps. The number of giant frame ports is ≤ 2; Confirm that all macro frame links are gigabit; Attempt to reduce the size of giant frames

After misconnecting a PoE device, the switch does not respond and the PoE voltage is damaged. The internal circuit of the switch is immediately disconnected from the PoE device; Contact Beckhoff Service for repair (not covered by warranty)

After cascading multiple switches, the network is paralyzed and there are network loops (the spanning tree protocol is not enabled). Check the topology to ensure that there are no redundant loops; The CU series does not have STP and requires manual confirmation of ring free operation

The power LED is on but all port Link lights are off. If there is an internal fault or poor grounding in the switch, check if the PE grounding is reliable; Attempt to supply power separately to eliminate interference; If still ineffective, repair

Environmental and UL Compliance Precautions

Working temperature: 0~55 ° C, avoid approaching heating elements to ensure convective heat dissipation.

Storage temperature: -25~85 ° C, avoid severe vibration during transportation (in accordance with EN 60068-2-6).

Protection level: IP20 (only applicable to dry and clean control cabinets), strictly prohibited from use in damp and dusty environments.

UL certification: Switches are only compatible with Beckhoff's UL Listed EtherCAT system and must not be connected to telecommunications circuits (such as telephone lines). When used in the North American market, it is essential to comply with 4A fuses or NEC Class 2 power supply requirements.

Maintenance and scrapping

There are no user replaceable components inside the switch. When cleaning, only wipe the outer shell with a dry soft cloth and do not use solvents.