934
Basic I/O Unit Instructions Section 3-23
The following table shows how DLNK(226) differs from FIORF(225) and
IORF(097).
DLNK(226) refreshes data between the CPU Unit and specified CPU Bus
Unit. There are two special factors to consider when using DLNK(226):
1,2,3... 1. When exchanging data through a data link or DeviceNet remote I/O com-
munications, the data exchange is not performed with the other Units at the
same time that DLNK(226) is executed. The data exchange will be per-
formed when the network communications cycle reaches the Unit in ques-
tion and data is exchanged with that Unit. Consequently, the actual data
exchange may be delayed by as much as the communications cycle time
of the network.
2. DLNK(226) cannot perform I/O refreshing with a CPU Bus Unit if that Unit
is currently exchanging data. If DLNK(226) is executed too frequently, I/O
refreshing will not be performed. We recommend allowing a delay between
executions of DLNK(226) that is longer than the communications cycle
time.
Instruction Operation
IORF(097) • I/O refreshing of words used by Basic I/O Units
• I/O refreshing of the CIO words and DM words used by Special
I/O Units
FIORF(225) • I/O refreshing of the CIO words and DM words used by a Spe-
cial I/O Unit
DLNK(226) • I/O refreshing of the CS1 CPU Bus Unit Area in the CIO Area
(25 words)
• I/O refreshing of the CS1 CPU Bus Unit Area in the DM Area
(100 words)
• Refreshing of data specific to the CPU Bus Unit, such as data
link data or DeviceNet Remote I/O Communications data
CPU Unit
CPU Bus Unit with
unit number N
Data areas used by the CPU
Bus Unit with unit number N
Words allocated
in CIO Area
Words allocated
in DM Area
Data link area
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