Glossary
222
SICAM I/O Unit, 7XV5673, Device Manual
E50417-H1040-C484-A3, Edition 05.2012
I
IEC
I
nternational
E
lectrotechnical
C
ommission, standards organization; Communica-
tion standard for substations and protection equipment
IP
I
nternet
P
rotocol
IP address
Addresses in computer networks based on the Internet protocol
J
JavaScript
Script language mainly used by Web browsers
K
Keep Alive
KeepAlive on TCP level is a feature intended to verify the availability and
functioning of the communication partner (client) and to maintain a TCP network link
if the network is inactive.
The server sends KeepAlive messages (TCP packets without data) to the client in
regular intervals (KeepAlive time) while the network is inactive, and the client
responds to these messages.
If the client does not respond to a KeepAlive message, the server assumes that the
link is down or the client is inactive and closes the TCP link.
L
LED
L
ight-
E
mitting
D
iode
LSB
L
east
S
ignificant
B
it
M
MAC Address
M
edia
A
ccess
C
ontrol address: Hardware address that clearly identifies the device
on the network.
MBAP
M
od
b
us
A
pplication
P
rotocol
MBAP Header
Header of a Modbus TCP message consisting of these 4 parts: Transaction identi-
fier (2 bytes), protocol identifier (2 bytes), length (2 bytes), unit identifier (1 byte).
Modbus
The Modbus protocol is a communication protocol based on a client-server
architecture.
Modbus RTU
Modbus
R
emote
T
erminal
U
nit: Modbus protocol type for transmitting data over
serial networks (for example RS485)
Modbus TCP
Modbus
T
ransmission
C
ontrol
P
rotocol: Modbus protocol type for transmitting data
as TCP/IP packets; TCP port 502 is reserved for Modbus TCP.
Modbus UDP
Modbus
U
ser
D
atagram
P
rotocol: Modbus protocol type for transmitting data as
UDP/IP packets
MSB
M
ost
S
ignificant
B
it
N
NO
N
ormally
o
pen: Type of relay
NTP
N
etwork
T
ime
P
rotocol: Standard for synchronizing clocks in computer systems
using packet-based communication networks
R
Response time
Time the output needs to react to a signal change at the device input. Time
measured from an instant change at the AC input until the corresponding change of
a DC output quantity has reached 90% of its final value.
RJ45
Ethernet plug connector
MAN_SICAM_IO-Unit_7XV5673_US.book Page 222 Thursday, May 10, 2012 10:59 AM