The EISM miniature switching hub is designed to be used where space is at a premium because of shrinking panels and the space restrictions of small machines.
The EISM5-100T is designated as a 5-port miniature switching hub. One port has an extra socket allowing it to be used as an uplink port to connect two switches together, thereby eliminating the need for a crossover cable. This unit is similar in function and capabilities to its EIS8-100T counterpart. It divides the Ethernet network into as many as five separate collision domains. It terminates the collision domain at each port. It functions as a "bridge" between these various data links — creating a larger network diameter than can be achieved with repeating hubs. Each port automatically negotiates with its attached device the data rate (10 or 100 Mbps) and duplex (full- or half-duplex) for that port. The flow control mechanism is also negotiated. For full-duplex segments, the PAUSE scheme is used. For half-duplex segments, the backpressure method is automatically invoked.
The switch learns the port locations of Ethernet devices by reading complete Ethernet frames and observing source addresses. A table of source addresses and corresponding port assignments is created and maintained. From that time on, traffic is restricted to only those ports involved in a transmission. This allows enhanced throughput since simultaneous transmissions can now be initiated on those ports without activity. Also, table values are aged to automatically accommodate changes to the field wiring. If a unicast transmission to an unknown destination is received on a port, all other ports are flooded with the transmission. This is also true of broadcast or multicast transmissions.
Link integrity is monitored, verifying that a working adapter or hub is on the distant end of a segment. To aid troubleshooting, each port LED glows solid if a link exists, flashes to show activity and shows data rate by color: green for 100 Mbps and yellow for 10 Mbps. One green power LED is provided.
Other features include wide-range, low-voltage AC or DC power requirements. Provisions exist for redundant power connections. The unit mounts on TS-32 or TS-35 DIN-rail, making it simple to install into industrial control panels.