Contents
MVI69-GEC ♦ CompactLogix or MicroLogix Platform
User Manual
Page 68 of 86
ProSoft Technology, Inc.
February 18, 2014
Word
Offset
Description
0
Block Sequence Number (Read block number as set by module)
Transmit
Data
1
Server Number for data to transmit. If the word contains a value of -1, no
transmit data is present. If the word contains a value from 0 to maximum
number of servers -1, the block contains data to send to the specified
server in the module.
2
Number of characters to transmit to server. Each block can transmit up to
118 bytes (59 words) of data. If this word contains a value of -1, the block
contains 118 bytes (59 words) of data and more blocks of data are to
follow. When the module received the last block containing a positive
value representing the number of bytes in the block, the server will
transmit the data to the client.
3 to 61
118 bytes (59 words) of data to transmit on specified server.
62
Server Control Word
63
Module Control Word Transmit Data
The Block Sequence Number is received on the last read block transfer through the Input
Image on the module. The ladder logic should copy this value from word 0 of the Input
Image to word 0 of Output Image in the ladder logic. This is the last operation performed
when constructing the write block. The module’s program will trigger the process write block
function when a new value is recognized in word 0 of the Output Image.
Word 1 of the block defines the server index that should receive the message. If the word is
set to a value of -1, there is no data in the message. A value of 0 to 4 will cause the
enclosed message to be sent to the server if the message length is set to a value other than
zero and the server has an open connection. Word 2 of the block defines the length of data
in the block. Up to 110 bytes (55 words) of data can be sent in each block starting at word
offset 3 in the block. If the message to be sent to a server is longer than 110 bytes (55
words), multiple blocks are required. As long as more than 110 bytes (55 words) are
required to send, the message length field should be set to a value of -1 and 110 bytes (55
words) of data should be placed in the block. When 110 or fewer bytes (55 words) remain to
be sent, the message length field should be set to that value and the remaining data placed
in the block. The server will accept messages up to a length of 4096 bytes (2048 words). If a
message longer than 4096 bytes (2048 words) is sent to a server, a transmit overflow error
will be recorded and the message will be sent when 4096 bytes (2048 words) are received.
The remaining part of the message will be sent as it is received.
The last two words of the image control the server or the module. The server control word
(word 62) controls the server. The following table lists the values recognized by the module:
Code
Definition
0
No operation to perform
1
Close socket after transmit operation
2
Abort socket after transmit operation
If a value of 0 is present in the field, no action is taken by the server. If a value of 1 is
present in the field, the server will gently close the socket after it transmits the message
contained in the block. If a value of 2 is present, the server will send the message contained
in the block and then force the connection closed by sending a reset message to the client.
