Cascading devices for distances higher than 100m by RS485

Since cascading converters and peripherals are quite fundamental and play a key role with respect to the project and project documentation, and subsequently implementation, we have decided to expand the basic article: https://photomate.zendesk.com/hc/en-gb/articles/9546743540381-Rules-for-cascading-devices-via-RS485 with our knowledge/experience

The most basic problem is the distance between peripherals. The manufacturer specifies stable and reliable communication between components up to 100m. When using a shielded cable with sufficient cross-section, stable communication without failures can be achieved even at 120-150m.

However, the reality is that few projects are able to meet these distances. Therefore, in cooperation with our partner, we have tested a solution in the form of RS485 - Metalic = Optical fieber converters.

As the most reliable and tested solution, we consider the following device: MOXA TCF-142-S

With this device, communication between SM3000 and Janitza CBM 103 over a distance of 4500m of optical fiber worked reliably for us.

Note: We reccomended to read manual carefully before instalation and put the hardware switches durring your actual connection. Or up to connecting 120 Ohm of resistance.

Be careful and connect right optical fiebers between Tx - Rx and Rx - Tx.