User Manual Owner manual

Chapter 2
Planning to Use Your ControlNet
PLC5 Processor
2-10
DescriptionMapTable Entry Field
Input File and Size
This is the offset in the input file where the data is to be stored and the number of words to be received from
the input device. For discrete I/O data transfer, the offset is into the inputimage table; for nondiscrete I/O
data transfer or peertopeer communication with another ControlNet processor, the offset is into the Data Input
File entered on the ControlNet configuration screen. Scheduled peertopeer inputs can also use the
inputimage file.
Output File and Size This is the offset in the output file where the data is located and the number of words of the output transfer.
For discrete I/O data transfer, the offset is into the outputimage table; for nondiscrete I/O data transfer or
peertopeer communication with another ControlNet processor, the offset is into the Data Output File (DOF)
entered on the ControlNet configuration screen. Scheduled peertopeer outputs can also use the
outputimage file.
Status File Offset This is an offset in a status file that points to three words of information on the status of this maptable entry.
Configuration File and Size Used only in 1771 nondiscrete I/O data transfer and 1794 configurations, this is the offset in a configuration
file where configuration information needed for this node is located and the size in words of the information.
Discrete I/O DataTransfer Mapping
Regardless of the type of I/O—e.g., 1771, 1794—all ControlNet discrete
I/O data is stored within the processor’s I/O image files according to the
corresponding I/O map-table entry. Any status information transferred
along with the I/O data is stored in a separate status file that you specify
during configuration.
Nondiscrete I/O DataTransfer Mapping
All ControlNet non-discrete I/O data is stored in integer files that you
specify in a ControlNet configuration screen. The ControlNet processor
supports two distinct image files; both are integer data-table files that
you specify:
Data Input File (DIF)
Data Output File (DOF)
Each map-table entry for a non-discrete I/O data transfer defines an offset
into the DIF or DOF where the data is stored. Using separate data-table
files for non-discrete I/O data transfer allows the processor to present
non-discrete I/O data in the same way as discrete I/O data—continuously
transmitted and asynchronous to the ladder-logic program scan.
1771 Modules
ControlNet 1771 discrete I/O data-transfer mapping requires one map-table
entry per module. ControlNet 1771 non-discrete I/O data-transfer mapping
requires one or two map-table entries per module, depending on the
module type.
The PLC-5/20C and -5/40C ControlNet non-discrete I/O data-transfer
mechanism makes it possible to eliminate block-transfer programming to
communicate with the 1771 modules listed in Table 2.G.