ProSoft Technology MVI56E-GSC/ GSCXT - Manual (Page 80)

Reference MVI56E-GSC ♦ CompactLogix or MicroLogix Platform
User Manual Enhanced Generic ASCII Serial Communication Module
Page 80 of 140 ProSoft Technology, Inc.
May 9, 2014
4.2.1 Backplane Data Transfer
The MVI56E-GSC module communicates directly with the ControlLogix either
through the backplane, when in a local chassis, or over a process I/O network
(like ControlNet or EtherNet/IP) when in a remote chassis. Data travels between
the module and the ControlLogix processor across the backplane or I/O network
using the module's input and output images. The I/O image update frequency is
determined by the scheduled Requested Packet Interval (RPI) time set by the
user for the module, as well as the overall communication load on the module.
Typical updates are in the range of 1 to 10 milliseconds.
Data received on the application ports is placed in the module's input image. This
data is processed by the logic in the ControlLogix processor. The input image
size for the module is set to 500 bytes. This large data area permits fast
throughput of data between the module and the processor.
The processor inserts data in the module's output image to transfer that data to
the module. The module's program extracts the data and transmits it out the
communication port or ports. The output image size for the module is set to 496
bytes. This large data area permits fast throughput of data from the processor to
the module.
The following illustration shows the data transfer method used to move data
between the ControlLogix processor, the MVI56E-GSC module and the serial
devices.
MVI56E-GSC Module