Factory price RS-232/ RS-485 to RS-485 hub with 4 ports. It has a transmission distance of more than 1200 meters and stable performance. 

Specification

Dimension (mm/ inch)

Tips: Working Principle of Hub signal forwarding?

The hub works at the MAC (Medium Access Control) sublayer of the physical layer and the data link layer of the OSI/RM reference model. The physical layer defines electrical signals, symbols, line status and clock requirements, connectors for data encoding and data transmission. Because the hub only reshapes and amplifies the signal and then retransmits it without coding, it is a physical layer device.

The hub uses the CSMA/CD (carrier frame listening multiple access/conflict detection) protocol. CSMA/CD is the MAC layer protocol, so the hub also contains the content of the data link layer.
As a special multi-port repeater, the 10M hub must follow the 5-4-3 rule in the network relay expansion, that is: a network segment can only be divided into 5 sub-network segments; a network segment can only be There are 4 repeaters; a network segment can only have up to three sub-network segments containing PCs.

The working process of the hub is very simple. It can be described simply as follows: First, the node sends a signal to the line, and the hub receives the signal. Because the signal is attenuated during cable transmission, the hub will reshape and amplify the attenuated signal after receiving the signal. The hub broadcasts the amplified signal and forwards it to all other ports.