ProSoft Technology MVI56E-MNETR - Manual (Page 105)

Reference MVI56E-MNETR ♦ ControlLogix Platform
User Manual Modbus TCP/IP Interface Module with Reduced Data Block
ProSoft Technology, Inc.
Page 105 of 153
August 31, 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
ControlLogix processor to interface the input and output image data with data
defined in the Controller Tags. All data used by the module is stored in its internal
database. This database is defined as a virtual Modbus data table with
addresses from 0 (40001 Modbus) to 4999 (45000 Modbus). The following
illustration shows the layout of the database:
Module’s Internal Database Structure
5000 registers for user data 0
Register Data
4999
Data contained in this database is paged through the input and output images by
coordination of the ControlLogix ladder logic and the MVI56E-MNETR module's
program. Up to 40 words of data can be transferred from the module to the
processor at a time. Up to 40 words of data can be transferred from the
processor to the module. Each image has a defined structure depending on the
data content and the function of the data transfer. The module uses the following
block numbers:
Block Range Descriptions
-1 Status block
0 Status block
1 to 125 Read or write data
1000 to 1124 Output Initialization Blocks
2000 Event Command Block
5001 to 5006 Command Control
9956 Formatted pass-through block from function 6 or 16 with word data.
9957 Formatted pass-through block from function 6 or 16 with floating-point data.
9958 Formatted pass-through block from function 5.
9959 Formatted pass-through block from function 15.
9960 Formatted pass-through block from function 22.
9961 Formatted pass-through block from function 23.
9970 Function 99 indication block.
9996 Unformatted Pass-through block with raw Modbus message.
9998 Warm-boot control block
9999 Cold-boot control block
These block identification codes can be broken down into a few groups: Normal
data transfer blocks (-1 to 125), Initialization blocks (1000 to 1124), Command
control blocks (2000, 5001 to 5006, 9998 and 9999) and pass-through function
blocks (9956 to 9961, 9970 and 9996).