ProSoft Technology inRAx MVI56-BDW, User Manual

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Reference MVI56-BDW ♦ ControlLogix Platform
BARDAC Drive Web Interface
ProSoft Technology, Inc. Page 61 of 82
September 4, 2008
The Write Block ID associated with the block requests data from the ControlLogix
processor. Under normal, program operation, the module sequentially sends
read blocks and requests write blocks. For example, if three read and two write
blocks are used with the application, the sequence will be as follows:
R1W1 R2W2 R3W1 R1W2 R2W1 R3W2 R1W1
This sequence will continue until interrupted by other write block numbers sent by
the controller or by a command request from a node on the network or operator
control through the module's Configuration/Debug port.
Write Block
These blocks of data transfer information from the ControlLogix processor to the
module. The structure of the output image used to transfer this data is shown
below:
Offset Description Length
0 Write Block ID 1
1 to 200 Write Data 200
201 to 247 Spare 47
The Write Block ID is an index value used to determine the location in the
module's database where the data will be placed. Each transfer can move up to
200 words (block offsets 1 to 200) of data.
Initialize Output Data
When the module performs a restart operation, it will request blocks of output
data from the processor to initialize the module's output data. This mode is
selected using the
Initialize Output Data
parameter in the configuration file. Use
the
Initialize Output Data
parameter in the configuration file to bring the module
to a known state after a restart operation. The structure of the block used to
request the data is displayed below:
Offset Description Length
0 Reserved 1
1 1000 to 1024 1
2 to 248 Spare 246
249 1000 to 1024 1
The block number in word 249 of the block determines the data set of up to 200
output words to transfer from the processor. Ladder logic in the processor must
recognize these blocks and place the correct information in the output image to
be returned to the module. The format of the returned write block is shown below:
Offset Description Length
0 1000 to 1024 1
1 to 200 Output Data to preset in module. 200
201 to 247 Spare 47