ProSoft Technology MVI56E-MNETR - Manual (Page 109)

Reference MVI56E-MNETR ♦ ControlLogix Platform
User Manual Modbus TCP/IP Interface Module with Reduced Data Block
ProSoft Technology, Inc.
Page 109 of 153
August 31, 2009
The Internal DB Address parameter specifies the module’s database location to
associate with the command. The Point Count parameter defines the number of
points or registers for the command. The Swap Code is used with Modbus
functions 3 and 4 requests to change the word or byte order. The Modbus
Function Code has one of the following values 1, 2, 3, 4, 5, 6, 15 or 16. The
Device Database Address is the Modbus register or point in the remote slave
device to be associated with the command.
When the module receives the block, it will process it and place it in the
command queue. The following table describes the format of this block.
Word Description
0 This word contains the block 2000 identification code to indicate that this block
contains a command to execute by the Client Driver.
1 to 4 These words contain the IP address for the server the message is intended.
Each digit (0 to 255) of the IP address is placed in one of the four registers.
For example, to reach IP address 192.168.0.100, enter the following values in
words 1 to 4
→192, 168, 0 and 100. The module will construct the normal
dotted IP address from the values entered. The values entered will be anded
with the mask 0x00ff to insure the values are in the range of 0 to 255.
5 This word contains the TCP service port the message will be interfaced. For
example, to interface with a MBAP device, the word should contain a value of
502. To interface with a MNET device, a value of 2000 should be utilized. Any
value from 0 to 65535 is permitted. A value of 502 will cause a MBAP
formatted message to be generated. All other values will generate an
encapsulated Modbus message.
6 This word contains the Modbus node address to use with the message. This
field should have a value from 0 to 41.
7 This word contains the internal Modbus address in the module to be used with
the command. This word can contain a value from 0 to 4999.
8 This word contains the count parameter that determines the number of digital
points or registers to associate with the command.
9 The parameter specifies the swap type for the data. This function is only valid
for function codes 3 and 4.
10 This word contains the Modbus function code to be used with the command.
11 This word contains the Modbus address in the slave device to be associated
with the command.
12 to 41 Spare
The module will respond to each command block with a read block. The following
table describes the format of this block.
Offset Description Length
0 Write Block ID 1
1 0=Fail, 1=Success 1
2 to 40 Spare 39
41 2000 1
Word two of the block can be used by the ladder logic to determine if the
command was added to the command queue of the module. The command will
only fail if the command queue for the port is full (100 commands for each
queue).