MVI56E-GEC ♦ ControlLogix Platform
Reference
Generic ASCII Ethernet Communication Module
User Manual
ProSoft Technology, Inc.
Page 57 of 80
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)
The Block Sequence Number (word offset 249) is an index value that signals to
the ControlLogix processor that a new block is ready for processing. The ladder
logic must recognize a change in this value, and then process the data
encapsulated in the input image. If data is available for a server, the module
passes a block containing data received and the complete status data area to the
processor. The value at word 0 in the block contains one of the following values:
Value
Description
-1
No receive data in block
0
Server 0 data in block
1
Server 1 data in block
2
Server 2 data in block
3
Server 3 data in block
4
Server 4 data in block
10
Client 0 data in block
11
Client 1 data in block
12
Client 2 data in block
13
Client 3 data in block
14
Client 4 data in block
Word 1 of the input image determines the number of bytes in the data area of the
block. This word only has significance if word 0 of the block is set to a valid
server index value (0 to 4), or client index value (10 to 14).
