Application notes

Used for: Standard Ethernet 10/100 Mbit

An Ethernet connection is a managed point-to-point connection between two intelligent end devices.

Both devices send a so-called idle sample to their Ethernet connection. The link has been established if a corresponding sample is received. Both devices then know that they can use this connection. If the connection is interrupted, the link is lost and both devices are notified.

If a media converter is placed between the two stations, it too becomes an intelligent transmitter/receiver. If connection C is interrupted, device A would not necessarily be informed and would continue to send data to the converter via the existing link B, and the data would "trickle away". The CU15x1 therefore supports Link Loss Forwarding (LLF) in a selected direction. The notification is indicated by a label on the CU15x1. If the converter detects an interruption of connection C in switch setting 1 in Fig. Interposed media converter in the Ethernet connection, it also interrupts link B.

In both IP settings the CU15x1 operates as a store and forward network device with checksum function. Frames that are faulty (CRC error), too short (< 64 bytes) or too long (> 1522 bytes) are not passed on.

Used for: EtherCAT 100 Mbit

Other characteristics are required if it is used as a media converter in an EtherCAT network:

• Consistently low delay in the frame transit, irrespective of frame length
• Fast link detection when the connection is established and interrupted
• Identification as separate EtherCAT device with diagnostic function

EtherCAT slaves process the EtherCAT telegrams in forward direction from the perspective of the master. Accordingly, in the CU15x1 the forward direction may be X1 --> X2 or X2 --> X1, depending on the application. It has to be set at the rotary switch prior to commissioning. The direction of the arrow of S1 indicates the set forward direction.

Make sure the rotary switch is set to the right position, so that the CU15x1 operates in forward direction. For example, in Fig. Copper -> optical fiber-> copper operation of two media converters, the CU15x1 on the left operates as a copper --> optical fiber converter (rotary switch position 5), the CU15x1 on the right operates as an optical fiber --> copper converter (rotary switch position 0).

If the opposite direction of rotation is set, the subsequent behavior depends on the EtherCAT master. The scanned CU15x1 may be inserted at a different position in the topology, or an INIT_VPRS error message of the EtherCAT master may occur.

Frame size in Ethernet mode In Ethernet mode only a frame size from 64 to 1522 bytes is supported.

Operating and application notes for SFP modules with the CU1521-0020

EtherCAT mode

• All 3 ports X1, X2, X3 are in operation in the order designated by rotary switch
• The CU1521-0020 can be used as a 2-port media converter or as a 3-port branch with media converter function
• The ports X1/X2 can be equipped with different SFP, at least one is necessary (see following SFP note)
• 100Mbit EtherCAT is supported (as of 2023), Gbit EtherCAT is in preparation (nevertheless 1Gbit-SFP are needed!)
• Only SFP modules approved by Beckhoff should be used to ensure EtherCAT suitability

Ethernet mode

• The 2 ports X1 and X3 are in operation - the device works as a media converter
• Different speeds (10Mbit, 100Mbit, 1Gbit) can be applied to port X1 and X3.
• The device works in store-and-forward principle
• Port X1 must be equipped with a SFP (see following SFP note)
• The device supports "Link Loss Forwarding”

Application notes for SFP modules The SFP is not sold by Beckhoff as an accessory and is not part of the scope of delivery. A functional guarantee and compatibility with all SFPs available worldwide cannot be given by Beckhoff. When procuring the SFP individually, the following points must be observed - the suitable operating temperature range of the SFP - no use of 100 Mbit modules, only 1Gbit SFPs are permitted - no SFP+ modules (SFP+ means >1Gbit) In EtherCAT operation, the SFP used must not impair operation (line control, timing). The following types have been qualified by Beckhoff (as of 2023): - Cisco GLC-BX40-D-I and GLC-BX40-U-I, bidirectional optical fiber, LC/PC, 40km, 1550/1310nm. - FS 36888 and 36889, Bidirectional optical fiber, LC/PC, 40km, 1550/1310nm

Earthing/Shielding

The FE contact on the supply socket must be directly connected to the mounting rail contact. During assembly, always take care of a conductive connection to the mounting rail.

Firmware update

A firmware update via EtherCAT is not possible for devices of the CU15x1 series

General notes

The CU15x1 deals with setting the rotary switch when the supply voltage is applied, unless the rotary switch is in an invalid position. In this case the CU15x1 deals with the setting when the rotary switch reaches a valid position for the first time.

If the rotary switch is moved during valid operation, the CU15x1 does not alter its function but indicates this state through its LED, see Diagnostics. The switch setting must be rectified before the voltage is re-applied!

Slanting installation of the optical fiber socket in the CU15x1 reduces the bending radius of the optical fiber cable during connection in the control cabinet (Fig. Slanting installation of the optical fiber socket).