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DEFINITIONS OF TERMINOLOGY
Term Description
Cyclic transmission
A function by which data are periodically exchanged among stations on the network using
link devices
Transient transmission
A function of communication with another station, which is used when requested by a
dedicated instruction or GX Developer
Link dedicated instruction Dedicated instruction used for transient transmission.
RAS
Abbreviation for Reliability, Availability, and Serviceability.
This term is used to express the overall usability of automation systems.
Control station
Only one station that controls the network to which it is connected.
Each station's send range for cyclic transmission is assigned to the control station.
Normal station
Station that performs cyclic transmission according to the range assignment of the control
station.
Reserved station
Station that is not actually connected to the network.
It must be included in the total number of stations in the network, since it is to be connected
in the future.
Relay station
A station that includes two or more network modules. Data are passed through this station
to stations on other networks.
Reconnection Processing of restarting data link when a faulty station becomes normal.
Disconnection Processing of stopping data link when a data link error occurs.
Device Devices (X, Y, M, D, etc.) that are contained in a CPU module.
Link Device Devices (LB/LW/LX/LY) that are contained in a network module.
Link scan time
Time required for data of each station to be sent in order and to make one rotation in the
network.
The link scan time changes depending on the data volume or transient transmission
request.
Link scans are performed "asynchronously" with sequence scans of the CPU module.
Link refresh
Processing of data transfer between link devices of the network module and CPU module
devices.
Link refresh is performed in "END processing" of the sequence scan of the CPU module.
Buffer memory
Memory area in an intelligent function module, in which data are temporarily stored.
The network module does not have any buffer memory area that is offered to the user.
Baton pass
A control mechanism in which transmission right (token) is passed around the network for
data transmission.
Control station shift time
Time taken from when the control station went down due to a reason such as power-off
until data link is started by the sub-control station.
Group No.
Number that is assigned for transient transmission to any given stations.
By specifying a group of stations as transient transmission target, data can be sent to the
stations of the same group No.
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