ProSoft Technology MVI56-DFCMR - Manual (Page 74)

MVI56-DFCMR ♦ ControlLogix Platform Reference
DF1 Interface Module with Reduced Data Block
Page 74 of 113 ProSoft Technology, Inc.
October 20, 2008
5.2.2 Data Flow between MVI56-DFCMR Module and ControlLogix
Processor
The following topics describe the flow of data between the two pieces of
hardware (ControlLogix processor and MVI56-DFCMR module) and other nodes
on the DF1 network under the module's different operating modes. Each port on
the module is configured to emulate a DF1 master device or a DF1 slave device.
The operation of each port is dependent on this configuration. The sections
below discuss the operation of each mode.
Slave Driver
The Slave Driver Mode allows the MVI56-DFCMR module to respond to data
read and write commands issued by a master on the DF1 network. The following
flow chart and associated table describe the flow of data into and out of the
module.
Step Description
1 The DF1 slave port driver receives the configuration information from the ControlLogix
processor. This information configures the serial port and define the slave node
characteristics. The module simulates N-files to permit remote access of the database.
Each file has a fixed length of 200-word registers.
2 A Host device, such as the Rockwell Automation PLC or an HMI application issues a
read or write command to the module's node address. The port driver qualifies the
message before accepting it into the module.
3 After the module accepts the command, the data is immediately transferred to or from
the internal database in the module. If the command is a read command, the data is read
out of the database and a response message is built. If the command is a write
command, the data is written directly into the database and a response message is built.
4 After the data processing has been completed in Step 3, the response is issued to the
originating master node.
5 Counters are available in the Status Block that permit the ladder logic program to
determine the level of activity of the Slave Driver.