Siemens OSM, ESM Properties of the TP/ITP Ports, Link Control, Auto Polarity Exchange

Interfaces, Displays and Operator Controls

4.1.3Properties of the TP/ITP Ports

Link Control

OSMs/ESMs monitor the connected TP/ITP cable segments for short-circuits or wire breaks using regular link test pulses complying with the 100BASE-TX standard. OSMs/ESMs do not send data to a segment from which they are not receiving link test pulses. An unused interface is taken to be a wire break since the device without power cannot send link test pulses.

Auto Polarity Exchange

If the receive cable pair is incorrectly connected (RD+ and RD- swapped over), the polarity is automatically reversed.

Autonegotiation Mode

The TP/ITP ports of OSM/ESM are set to the autonegotiation mode.

They automatically detect the transmission rate (10 or 100 Mbps) at which the attached device or attached network segment operates and set themselves to this rate. If the partner device also supports the autonegotiation mode, the devices further negotiate whether they will exchange data with each other in the half duplex or full duplex mode.

Note

If the partner device connected to a port of an OSM/ESM does not support the autonegotiation mode (for example OSM Version 1), the port of the partner device must be set to half duplex mode.

Autocrossover Function

OSMs/ESMs with digital inputs are capable of switching over their TP/ITP ports automatically between MDI and MDI-X pinning; in other words, they can cross over the send and receive data internally, when necessary.

This means that regardless of the port type of the device you are connecting and the type of Ethernet cable, a connection can be established. Crossover cables are not necessary.

Industrial Ethernet OSM/ESM	45
C79000-Z8976-C068-10