ProSoft Technology MVI69-ADM - Manual (Page 43)

MVI-ADM ♦ 'C' Programmable Understanding the MVI-ADM API
'C' Programmable Application Development Module Developer's Guide
ProSoft Technology, Inc. Page 43 of 342
February 20, 2013
MVI71 Backplane Data Transfer
The MVI71-ADM module communicates directly over the backplane. Data is
paged between the module and the PLC processor across the backplane using
the module's input and output images or directly to the processor using the side-
connect interface (requires a side-connect adapter). The update frequency of the
images is determined by the scheduled scan rate defined by the user for the
module and the communication load on the module. Typical updates are in the
range of 2 to 10 milliseconds.
This bi-directional transference of data is accomplished by the module filling in
data in the module's input image to send to the processor. Data in the input
image is placed in the Controller Tags in the processor by the ladder logic. The
input image for the module is set to 64 words. This large data area permits fast
throughput of data between the module and the processor.
The processor inserts data to the module's output image to transfer to the
module. The module's program extracts the data and places it in the module's
internal database. The output image for the module is set to 64 words. 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 PLC processor, the MVI71-ADM module and the foreign device.
Block Transfer
The following illustration shows the data transfer operations used when using the
side-connect interface (requires the side-connect adapter):