Siemens Simantic ET 200S Manual page 268

Glossary
SNMP
SNMP (Simple Network Management Protocol) is the standardized protocol for performing
diagnostics and assigning parameters to the Ethernet network infrastructure.
In the office setting and in automation engineering, devices from many different vendors
support SNMP on the Ethernet.
SNMP-based applications can be operated on the same network in parallel to applications
with PROFINET.
The scope of supported functions depends on the device type. For example, a switch has
more function than a CP 1616.
SSI
The positional information is transferred synchronously on the basis of the SSI (synchronous
serial interface) protocol. The SSI protocol is used with absolute encoders.
Stationary wiring
All the wiring-carrying elements (terminal modules) are mounted on a rail. The power and
electronic modules are inserted in the terminal modules.
Switch
PROFIBUS is a linear network. The communication nodes are linked by means of a passive
cable– the bus.
By contrast, Industrial Ethernet consists of point-to-point connections: each communication
node is directly connected to exactly one communication node.
If a communication node is linked to several communication nodes, this communication node
is connected to the port of an active network component – the switch. Additional
communication nodes (including switches) can now be connected to the other ports of the
switch. The connection between a communication node and the switch remains a
point-to-point connection.
A switch also has the task of regenerating and distributing received signals. The switch
"learns" the Ethernet address(es) of a connected PROFINET device or additional switches
and only forwards those signals that are intended for the connected PROFINET device or
switch.
A switch has a specific number of ports. You connect at most one PROFINET device or
additional switch to each port.
SYNC
This is a control command of the DP master to a group of DP slaves.
By means of the SYNC control command, the DP master causes the DP slave to freeze the
current statuses of the outputs. With the subsequent frames, the DP slave stores the output
data, but the statuses of the outputs remain unchanged.
After each new SYNC control command, the DP slave sets the outputs that it has stored as
output data. The outputs are not cyclically updated again until the DP master sends the
UNSYNC control command.
Glossary-8
Manual, Edition 10/2005, A5E00514527-01
ET 200S