Reference MVI46-GEC
♦
SLC Platform
Generic ASCII Ethernet Interface Module
ProSoft Technology, Inc.
Page 47 of 78
April 30, 2008
The following illustration shows the data transfer method used to move data
between the SLC processor, the MVI46-GEC module, and the Ethernet network.
TCP/IP
Stack
and
Ethernet
Interface
Clients
TCP/IP
Servers
Transmit
Driver
Logic
Receive
Driver
Logic
M1 Files
M0 Files
MVI46-GEC Module
Bac
kpl
ane D
riv
e
r
Ethernet
Network
M0
files
M1
files
Status files
Read Data files
Write Data files
Special
Control
Blocks files
SLC Processor
Ladder
Logic
As shown in the diagram above, all data transferred between the module and the
processor over the backplane is through the M1and M0 files. Ladder logic must
be written in the SLC processor to interface the M-file data with data defined in
the controller. The user is responsible for handling and interpreting all data
received on the application ports and transferred to the M1 file. Additionally, the
user is responsible for constructing messages to be transferred out of the servers
by building the messages in the M0 file of the module
Normal Data Transfer
Normal data transfer includes the transferring of data received or to be
transmitted on the servers and the status data. These data are transferred
through read (M1 file) and write (M0 File) blocks. Refer to Module Configuration
for a description of the data objects used with the blocks and the ladder logic
required. The following topics discuss the structure and function of each block.
Read Block
These blocks of data transfer information from the module to the SLC processor.
The structure of the M1 file used to transfer this data is shown in the following
table:
Word
Offset
Description
Received
Data
0
Server/Client Number for data received. If the word contains a value of
-1, no receive data is present. If the word contains a value from 0 to 4,
the block contains data for one of the servers in the module. If the word
contains a value of 10 to 14, the block contains data for one of the
clients.
1 Number of characters (0 to 200) in receive block (2 to 101). If the
receive data in the module is larger than 200 bytes (100 words),
multiple blocks will be transferred. Any block with a value of -1 in this
field represents the first or continuation block and the block contains
200 bytes (100 words) of data. The last block of data will contain a
positive number in this field that represents the number of characters in
the last block.
2 to 101
200 bytes (100 words) of data received for specified server or client.
