ProSoft Technology MVI56E-MNET/MNETXT - Manual (Page 119)

MVI56E-MNET / MNETXT ♦ ControlLogix Platform Reference
Modbus TCP/IP Interface Module User Manual
ProSoft Technology, Inc. Page 119 of 181
April 23, 2014
5.2.2 Special Function Blocks
Special function blocks are optional blocks used to request special tasks from the
module.
Initialize Output Data Blocks (1000 to 1024)
Use the Initialize Output Data parameter in the configuration to bring the module
to a known state after a restart operation. If the Initialize Output Data parameter
is enabled, when the module performs a restart operation, it will request blocks of
output data from the ReadData array in the processor to initialize the Read Data
area of the module’s internal database.
Block Request from Module to Processor
Word Offset Description Length
0 Reserved 1
1 1000 to 1024 1
2 to 248 Spare 247
249 1000 to 1024 1
Ladder logic subtracts 1000 from the value contained in word 249 to determine a
block index. This bock index determines which 200-word block of data will be
taken from the ReadData array and placed in the output image to be returned to
the module.
Block Response from Processor to Module
Word Offset Description Length
0 1000 to 1024 1
1 to 200 Output data to preset in module. 200
201 to 247 Spare 47