ProSoft Technology MVI56E-MNETC - Manual (Page 113)

MVI56E-MNETC ♦ ControlLogix Platform Reference
Modbus TCP/IP Client Enhanced Communication Module User Manual
ProSoft Technology, Inc. Page 113 of 183
February 3, 2013
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 9999 (50000 Modbus).
Module’s Internal Database Structure
10,000 registers for user data 0
Register Data
9999
Data contained in this database is transferred in blocks, or pages, using the input
and output images. ControlLogix ladder logic and the MVI56E-MNETC module's
program work together to coordinate these block transfers. Up to 200 words of
data can be transferred from the module to the processor (read block - input
image) or from the processor to the module (write block - output image) in each
block transfer. The block structure of each block type depends on the data
content and function of the block. The module uses the following block
identification numbers:
Block ID Range Descriptions
-1 Null block
0 For firmware versions earlier than 2.05, this is a null block.
For firmware versions 2.05 and newer, block 0 contains the same data as
block 1. This feature enhances performance, especially when using less than
200 words of read/write data:

If Read Register Count in the module configuration file is set > 200 words,
Block ID 0 is not used.
 If Read Register Count in the module configuration file is set >0 and <=
200 words, Block ID contains the same data as block 1 (both read data
and status data).
1 to 50 Read or Write blocks
1000 to 1049 Initialize Output Data blocks
2000 to 2029 Event Command blocks
3000 to 3029 Client Status blocks
3100 Server Status block
4000 to 4029 Event Sequence Command blocks
4100 to 4129 Event Sequence Command Error Report blocks
4200 to 4229 Event Sequence Command Count Status blocks
5001 to 5016 Command Control blocks
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