
Interfaces, Displays and Operator Controls
Industrial Ethernet OSM/ESM
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C79000-Z8976-C068-04
4.1.3 Properties 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.
Auto-negotiation Mode
The TP/ITP ports of OSM/ESM are set to the auto-negotiation 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 auto-negotiation 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 auto-
negotiation mode (for example OSM Version 1), the port of the partner device must
be set to half duplex mode.
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