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

Function range
- FW01: only use in pairs possible, with identical SFP on both sides
- FW02 and higher: single use also possible, e.g. vs. EK1501 with corresponding SFP
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.
The following types have been qualified by Beckhoff (status 2025-03): - SingleMode
• Optomedia PT1-S1-4203L - MultiMode
• Optomedia PT1-M4-4023L - Bidirectional
• Cisco GLC-BX40-D-I and GLC-BX40-U-I, Bidirectional optical fiber, LC/PC, 40km, 1550/1310nm
• FS 36888 1000BASE-BX-D BiDi SFP 1550nm-TX/1310nm-RX 40km LC/PC (2024)
• FS 36889 1000BASE-BX-U BiDi SFP 1310nm-TX/1550nm-RX 40km LC (2024)
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” and reports the link loss in the direction indicated by the arrow.
![]() | Application notes for SFP modules The SFP is not sold by Beckhoff as an accessory and is not part of the scope of delivery. |