MVI56E-GEC ♦ ControlLogix Platform
Reference
Generic ASCII Ethernet Communication Module
User Manual
ProSoft Technology, Inc.
Page 55 of 80
6.2
Functional Overview
6.2.1 General Concepts
The following discussion explains several concepts that are important for
understanding module operation.
Module Power Up
On power up the module begins performing the following logical functions:
1
Initialize hardware components
o
Initialize ControlLogix backplane driver
o
Test and clear all RAM
o
Initialize the TCP/IP stack and Ethernet interface
2
Initialize servers and clients
After the module has received the configuration, the module will begin receiving
and transmitting messages with clients and servers on the Ethernet network.
Backplane Data Transfer
The MVI56E-GEC module communicates directly over the ControlLogix
backplane. Data travels between the module and the ControlLogix processor
across the backplane using the module's input and output images. The update
frequency of the data is determined by the user-defined scan rate for the module,
and the communication load on the module. Typical updates are in the range of 2
to 10 milliseconds.
Data received by the module's clients and servers is placed in the module's
Database. This data is read and then processed by the ladder logic in the
ControlLogix processor through the Input Image (Local Input connection). The
input image parameter in Studio 5000 Logix Designer for the module is set to 250
registers (500 bytes).
The processor writes data through the Output Image (Local Output connection)
for transfer into the module's Database. The module's program extracts the data
from the module's Database and transmits the data out to the Ethernet network.
Each message is directed to a client or server that is connected to a remote host.
The Output image parameter in Studio 5000 Logix Designer for the module is set
to 248 registers (496 bytes). This large I/O area permits fast throughput of data
between the module and the processor.
