GFK-2571A
Chapter 1 Introduction
1-17
1
Glossary, continued
RDO
R
ecord
D
ata
O
bject. Services used to read and write structured data stored in a
PROFINET IO-Device.
Reduction
Ratio
Along with Send Clock determines the Update Period for a PROFINET cyclic data transfer
between two devices (see IOCR). The Update Period equals the Reduction Ratio
multiplied by the Send Clock time. For example, if the Reduction Ratio is 4 and the Send
Clock is 1ms, the Update Period is 4ms.
Remote Node
For an RX3i PROFINET network, a Remote Node is any PROFINET IO-Device, such as a
rack of I/O modules with a Remote Scanner or a third party PROFINET IO-Device.
RTA
R
eal-
T
ime
A
cyclic. A PROFINET-IO Mechanism used to exchange non-periodic data
such as alarms.
RTC
R
eal-
T
ime
C
yclic. A PROFINET-IO Mechanism used to exchange input and output data.
Send Clock
Value between 1 and 128 inclusive in 31.25 µs units (equivalent to a range of 31.25 µs to
4 ms) used to calculate the Update Period for a PROFINET cyclic data transfer between
two devices (see IOCR). The Send Clock is the basis for all other scheduling parameters.
Send Offset
The time to delay a scheduled PROFINET cyclic data transfer frame. Measured in
nanoseconds from 0 to 3,999,999. Must be less than the Send Clock time.
SFP
S
mall
F
orm-factor
P
luggable. Pluggable, hot-swappable transceivers.
SNMP
S
imple
N
etwork
M
anagement
P
rotocol. UDP-based network protocol that facilitates the
exchange of management information between network devices.
Status Bits
Module status data in RX3i CPU reference memory.
Submodule
PROFINET-IO representation of the smallest configurable entity of a PROFINET Module.
SVC_REQ
Service Request Function Block. A control system service initiated by the RX3i CPU.
Unicast
In Ethernet, the transmission of a network message to an individual host.
Update Period
The time between PROFINET cyclic data transfers between an IO-Controller and an
IO-Device.
