ProSoft Technology MVI56-GEC - Manual (Page 73)

MVI56-GEC ♦ ControlLogix Platform Reference
Generic ASCII Ethernet Communication Module User Manual
ProSoft Technology, Inc. Page 73 of 108
October 8, 2010
Normal Data Transfer
Normal data transfer includes data transmitted between clients and servers, and
status data. Data transfer takes place through read (input image) and write
(output image) blocks.
Refer to Installing and Configuring the Module 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 ControlLogix
processor. The following table shows the structure of the input image used to
transfer this data.
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, 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 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 of data received for specified server or client.
Module
Status
102 to 234 This data area contains the status data block. Each block transferred to
the processor contains this set of information.
IDs for
Servers,
Clients
and
Message
Blocks
235 to 246 Reserved for future use.
247
Value for designated Server or Client number during writing process (0-
4) for Servers (10-14) for clients.
248 Number of characters processed from last write block (0 to 400).
249 Block Sequence Number (Bumped each scan by module)