# Media link block: 802.5j/local wrap

The Smart 16/4 Fiber AT Ringnode works with a range of different fiber-optic concentrators. If your concentrator has been designed to meet the IEEE 802.5j draft-standard, set the link block so that the arrow points to 802.5j on the printed circuit-board. If not, set the link block so that the arrow points to Local wrap. The default is 802.5j.

The link block consists of two parts:

- A removable header block. This has two rows of holes on its underside and is marked with a bold arrow on its upper face.

- A base section fixed to the printed circuit-board. This has two rows of pins corresponding to the holes in the header.

| Fit the header block to cover all the pins on the base section. If it is misaligned, the Ringnode may not work correctly. Take care not to bend any of the pins when you remove or replace the header block.