Siemens ESM - Manual (Page 93)

Glossary
Industrial Ethernet OSM/ESM
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Latency The latency specifies the taken for packets to pass through the
OSM/ESM. It is assumed that a received packet can be sent on
immediately. The latency does not include the time necessary for the
OSM/ESM to receive a packet.
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.
MDI-X Medium Dependent Interface Crossover
RJ-45 jack with pinning of a network component
OSM Optical Switching Module. SIMATIC NET Ethernet switch with optical
and electrical ports
Reconfiguration Time Time required by the OSM/ESM operating in the redundancy manager
(RM) or standby mode to reestablish a functioning configuration if a
device fails or the cable is interrupted.
Redundancy Manager
(RM) Mode of an OSM or ESM for forming a redundant ring structure. The
RM monitors the OSM or ESM bus connected to it, closes the bus if it
detects and interruption. This reestablishes a functioning bus
configuration.
One and only one device can operate in the RM mode in every OSM or
ESM ring.
Signaling Contact Floating relay contact via which the error states detected by the
OSM/ESM can be signaled.
Standby-sync port Port of an OSM/ESM via which two OSMs or ESMs are interconnected
in a redundant ring link allowing them to inform each other of their
operating states (not available with the OSM TP22 and ESM TP40).
Store and forward In this switching method used on the OSM/ESM, the complete packet
is read in before it is passed on by the switch. A packet is only passed
on if it is error-free.
TP Port Port with a TP connector (RJ-45 jack)