ProSoft inRax MVI94-GSC-E, Руководство пользователя

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Reference MVI94-GSC-E ♦ FLEX Platform
User Manual Generic ASCII Comunication Module
ProSoft Technology, Inc.
Page 39 of 60
July 6, 2009
All data transferred between the module and the processor over the backplane is
through the input and output images. Ladder logic must be written in the Flex
processor to interface the input and output image data with data defined in the
processor. The user is responsible for handling and interpreting all data received
on the application port and transferred in the input image. Additionally, the user is
responsible for constructing messages to be transferred out of the application
port by building the messages in the output image of the module.
Each block transferred between the module and the processor has a block
number in byte zero of the input or output image.
Block ID Description
0 to 127 Normal data blocks for read and write
254 Warm boot module
255 Cold boot module
128 to 253 Reserved for future use
Block identification codes 0 to 127 are used for normal data transfer. Blocks 254
and 255 are used as control blocks to control the module from the ladder logic.
Blocks 128 to 253 are reserved and are intended for future use.
4.2.3 Normal Data Transfer
Normal data transfer includes the transferring of data received or to be
transmitted on the port and the status data. These data are transferred through
read (input image) and write (output image) blocks. The following topics describe
the function and structure of each block.
Read Block
These blocks of data transfer information from the module to the Flex processor.
When data is received on the port, blocks of the following structure are
constructed by the module in the input image:
Byte Offset Description
0 Block Sequence Number (Bumped each scan by module)
1 Number of characters (0 to 14) in Application Port receive block (2 to 15). If the
receive data in the module is larger than 14 bytes, multiple blocks will be
transferred. Any block with a value of 255 in this field represents the first or
continuation block and the block contains 14 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. If this block contains a value of 252 or 253 the block
contains status data.
2 to 15 Application Port data received
The Block Sequence Number (byte 0) is an index value used to signal to the Flex
processor that a new block is ready for processing. The ladder logic must
recognize a change in this value and process the data encapsulated in the input
image. Byte 1 of the block contains a count of the number of bytes to process in
the current block. Bytes 2 to 15 contain the data received on the port. If the
receive byte swapping option is enabled, the bytes received will be swapped
before being placed in the input image.