ProSoft Technology MVI69L-MBTCP - Manual (Page 55)

MVI69L-MBTCP ♦ CompactLogix Platform MVI69L-MBTCP Configuration
Communication Module User Manual
ProSoft Technology, Inc. Page 55 of 152
January 6, 2014
3.2.4 MBTCP Client x Commands
In order to interface the MVI69L-MBTCP module with Modbus server devices, a
command list needs to be created. The commands in the list specify the server
device to be addressed, the function to be performed (read or write), the data
area in the device to interface with and the registers in the internal database to
be associated with the device data.
Each of the 10 Client command lists supports up to 16 commands each. The
command list is processed from top (Command #0) to bottom.
Read commands are executed without condition. Write commands can be set to
execute only if the data in the write command changes (Conditional Enable). If
the register data values in the command have not changed since the command
was last issued, the command will not be executed. This feature can be used to
optimize network performance.
The MBTCP Modbus Client (and Server) communication drivers support several
data read and write commands. When a command is configured, the type of data
(bit, 16-bit integer, 32-bit float, etc), and the level of Modbus support in the server
equipment will need to be considered. For information on floating-point support,
please see the Floating-Point Support section on page 120.
Parameter Value Description
Enable Disable,
Enable,
Conditional Bit/Word
Override,
Float Override
This field defines whether the command is to be
executed and under what conditions.
Disable (0) = The command is disabled and will not be
executed in the normal polling sequence.
Enable (1) = The command is executed each scan of
the command list if the Poll Interval (see below) is set
to zero. If the Poll Interval is set to a nonzero value,
the command is executed when the interval timer
expires.
Conditional (2) = For write commands only. The
command executes only if the internal data associated
with the command changes.
Bit/Word Override (3) = For read commands only. If a
command error occurs, the module will override the
associated database area with the Override Value
Upon Error parameter value.
Float Override (4) = For read commands only. If a
command error occurs, the module will override the
associated database area (2x word count) with the
Override Value Upon Error parameter value.
Internal Address 0 to 479 (word-level)
or
0 to 3839 (bit-level)
Specifies the module’s internal database register to be
associated with the command. Allowable range is 0 to
9999 for Modbus Function Codes 3, 4, 6, or 16, and 0
to 65535 for Modbus Function Codes 1, 2, 5, or 15.
If the command is a read function, the data read from
the server device will be stored beginning at the
module’s internal database register value entered in
this field. This register value must lie within the Read
Data area of the module’s memory, defined by the