359
ifm
Device Manual SmartSPS AC14 with EtherNet/IP interface (AC1421, AC1422), Firmware 3.1.2
2015-11-30
Glossary of Terms
Symbols
Pictograms are figurative symbols which
convey information by a simplified graphic
representation. (
→ chapter
What do the symbols
and formats mean?
)
>
System variable
Variable to which access can be made via IEC
address or symbol name from the PLC.
>
T
Target
The target contains the hardware description
of the target device for CODESYS, e.g.: inputs
and outputs, memory, file locations.
Corresponds to an electronic data sheet.
>
TCP
The
T
ransmission
C
ontrol
P
rotocol is part of
the TCP/IP protocol family. Each TCP/IP data
connection has a transmitter and a receiver.
This principle is a connection-oriented data
transmission. In the TCP/IP protocol family the
TCP as the connection-oriented protocol
assumes the task of data protection, data flow
control and takes measures in the event of
data loss. (compare:
→UDP)
>
U
UDP
UDP (
U
ser
D
atagram
P
rotocol) is a minimal
connectionless network protocol which belongs
to the transport layer of the internet protocol
family. The task of UDP is to ensure that data
which is transmitted via the internet is passed
to the right application.
At present network variables based on
→CAN
and UDP are implemented. The values of the
variables are automatically exchanged on the
basis of broadcast messages. In UDP they are
implemented as broadcast messages, in CAN
as
→PDOs.
According to the protocol, these services are
unconfirmed data transmission: it is not
checked whether the receiver receives the
message. Exchange of network variables
corresponds to a "1 to n connection"
(1 transmitter to n receivers).
>
Unit ID
→Modbus
>
Use, intended
Use of a product in accordance with the
information provided in the instructions for use.
>
W
Watchdog
In general the term watchdog is used for a
component of a system which watches the
function of other components. If a possible
malfunction is detected, this is either signalled
or suitable program branchings are activated.
The signal or branchings serve as a trigger for
other co-operating system components to
solve the problem.