Siemens SIMATIC CP 541 Manual page 136

Communications processor
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Glossary
PROFIBUS DP
R
Response Delay
Time
S
SDA
SDN
SINEC L2
SINEC L2-DP
Slave
SRD
Station
Glossary-4
Draft standard PROFIBUS DP (DIN E 19245, Part 3) on which the distrib-
uted periphery (I/O) system is based.
The main task of PROFIBUS DP is fast cyclic exchange of data between the
central DP master and the peripherals.
You specify the duration of the response delay time with the configuring soft-
ware of the DP master.
If a DP slave is not addressed within the response monitoring time, it goes to
the safe state and all outputs are set to 0.
The CP 541 sends a zero message to the connected programmable controller.
Send Data with Acknowledge: SDA is a service used in PROFIBUS. The
addressed station confirms reception of the message.
Send Data with No Acknowledge: the SDN service is used in SINEC L2 if a
station wishes to send a message to two or more other stations. The addressed
stations do not confirm reception of the message.
SINEC L2 is a bus system for the networking of PROFIBUS-compatible au-
tomation systems and field devices in the cell and field level. SINEC L2 is
available with the following protocols: PLC-PLC, DP (distributed periphery
(I/O)), FDL (fieldbus data link), FMS (fieldbus message specification) and
TF (technological functions).
The SINEC L2 bus system with the DP protocol
A slave may only exchange data with a master when requested to do so by
the master.
Send and Request Data: SRD is a service used in PROFIBUS. The addressed
station confirms reception of the message or sends the requested data.
A station is a device which can send, receive or amplify data via the bus; for
example, master, slave, repeater, transceiver.
Communications Processor CP 541
EWA 4NEB 812 6188-02

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