ProSoft Technology MVI71-GSC - Manual (Page 50)

MVI71-GSC ♦ PLC Platform Reference
Generic Serial Communication Module
Page 50 of 82 ProSoft Technology, Inc.
January 31, 2008
5.1.7 Normal Data Transfer
Normal data transfer includes the transferring of data received or to be
transmitted on the ports and the status data. These data are transferred through
read and write blocks. The structure and function of each block is discussed
below:
Read Block
These blocks of data transfer information from the module to the PLC processor.
The structure used for the BTR operation is shown below:
Word Offset Description
0 Block Sequence Number (Bumped each scan by module) (0 to 127)
1 Number of characters (0 to 50) in Port 1 receive block (3 to 27). If the
receive data in the module is larger than 50 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 50 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 Number of characters transmitted (0 to 50) from last block write Port 1
Port 1
3 to 27 Port 1 data received (50-byte data area)