ProSoft Technology MVI56E-SIE - Manual (Page 140)

Reference MVI56E-SIE ♦ ControlLogix Platform
User Manual Client Communication Module
Page 140 of 168 ProSoft Technology, Inc.
September 6, 2012
Write Block
These blocks of data transfer information from the ControlLogix processor to the
module.
The following table describes the structure of the output image.
Write Block from Processor to Module
Word Offset Description Length
0 Write Block ID 1
1 to 200 Write Data 200
201 to 220 Command bit data for Clients (set) 20
231 to 246 Spare 16
247 Select Priority Read Block 1
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.
Select Priority Read Block (Write Block Offset 247)
This register allows the processor to select which read blocks will be returned
from the module. If this register equals zero, the module will return all read blocks
in sequential order.
If this register has a non-zero value, the module will return the read block
selected, and the following one.
This feature can be used for applications that require some read blocks to be
updated more frequently than other blocks.
The following illustrations show the effect of changing the value of the Select
Priority Read Block register (Write Block offset 247). In the following histogram
curve, the Select Priority Read Block is equal to 0.
 Local:1.O.Data[247] = Select Priority Read Block.
 Local:1.I.Data[249] = Read Block ID.