802
Basic I/O Unit Instructions Section 3-22
The following table shows how DLNK(226) differs from 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.
Flags
Instruction Operation
DLNK(226) • I/O refreshing of the CPU Bus Unit Area in the CIO Area (25
words)
• I/O refreshing of the 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
IORF(097) • I/O refreshing of words used by CPM1A Expansion I/O Units or
CPM1A Expansion Units
• I/O refreshing of the 10 CIO words allocated to a Special I/O Unit
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
Refresh
Name Label Operation
Error Flag ER ON if the specified unit number is not between 0000 and
000F hex (between 0 and 15 decimal).
ON if the PLC does not have a CPU Bus Unit with the
specified unit number.
OFF in all other cases.
Equals Flag = OFF if the I/O refreshing could not be performed because
the CPU Bus Unit was refreshing data.
OFF if there was an error or setting error in the specified
CPU Bus Unit.
OFF if DLNK(226) was executed in an interrupt task,
there was a conflict with regular I/O refreshing, and over-
lapping refreshing occurred.
ON if the I/O refreshing was completed normally.
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