bolinboy

The most common cause of failure of data links over fibre is due to delay timing, biasing errors or on RS485 links, termination errors. The delay timing is used to ensure the data transmit is complete before the RS485 driver changes state for the response. When equipment is installed at remote locations, the local earthing (grounding) is often very different. This leads to a mismatch in reference levels of the copper signal segments between the two ends of the fibre link. Biasing on a fibre tranceiver allows the relative reference levels to be adjusted to a better match. Most fibre optic tranceivers for CCTV use have dipswitch or rotary switches to adjust these settings. Check with your manufacturer for the adjustments available on your tranceivers and then try them out until you find the best match. If these switches are not available, you will need to use resistors/diodes to create the necessary biasing/termination values.