Glossary
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Trebing & Himstedt | SPI 3 | MODBUS RTU
Response timeout
The duration of time within which the partner device must
respond. The response timeout must be configured
identically for both partner devices.
Segment
Section of the bus cable between two terminating resistors.
A bus segment can support up to 32 bus stations, and
several bus segments can be connected together with RS
485 repeaters.
Send
The DP master sends a telegram to a Fieldbus device
through the SPI 3.
Send channel
Data channel for data which is sent to the SPI 3.
Slave
Bus station which is only allowed to exchange data with a
master, and only on request of the master.
Station address
Address with which the DP master accesses the PROFIBUS
DP slave.
Status byte
→
Mirror
Step
5
Programming language used for user programs for
SIMATIC S5 controllers.
Step
7
Programming language used for user programs for
SIMATIC S7 controllers.
Step 7 tool
Tool for Step 7 which automates particular programming
tasks.
SYNC
Control command that a DP slave receives from the DP
master. It causes the slave to store (freeze) the current
states of its outputs. When following telegrams are received,
it stores the output data, but the states of the outputs remain
unchanged. The outputs are only cyclically updated again
after the slave receives the UNSYNC command.
Telegram
A data flow which is sent or received through the serial
interface (SIO), e.g. when you send a text to a text display
or receive a bar code from a bar code scanner.
Terminating resistor
Used to stop electrical reflections and thus signal distortion
at the end of the bus cable. Terminating resistors are
required at each end of the bus cable.
