ProSoft Technology MVI46-MCM - Manual (Page 29)

MVI46-MCM ♦ SLC Platform Ladder Logic
Modbus Communication Module User Manual
ProSoft Technology, Inc. Page 29 of 108
March 29, 2011
3.1.3 Master Commands
These records define the commands in the master command list. Each
parameter is described in the following table.
Parameter Description
Enable This parameter defines if the command is executed or disregarded. The
following values are valid: 0=Disables the command and it will not
execute. 1=The command will be considered for execution each scan of
the command list and will be controlled by the PollInt parameter. And
2=The command will only execute if the data associated with the
command has changed since the command was last issued. This option
is only available for write commands.
IntAddress This parameter specifies the starting internal register address to be
associated with the command. Valid entry for this parameter is 0 to 4999
for Register Address (0 to 65535 for Bit Address).
Polllnt This parameter defines the minimum number of seconds to wait between
the execution of continuous commands (Enable=1). This poll interval
command can be used to lighten the communications load on a busy
network. Valid entry for this parameter is 0 to 65535.
Count This parameter defines the number of registers to be considered by the
command. Valid entry for this parameter depends on the Modbus
specification for the command.
Swap This parameter specifies if the data used in the command must be
altered when a Modbus function code 3 reads data from a node on the
network. Values that can be assigned are as follows: 0=no swapping of
data, 1=swap word values, 2=swap word and byte values and 3=swap
byte values. This option is used when interfacing the module with ASCII
and floating-point data on other devices.
Node This parameter assigns the Modbus slave node address for the module
to reach with the command on the Modbus network. This parameter can
be assigned values from 0 to 255. Most Modbus networks limit the upper
value to 247.
Func This parameter specifies the Modbus function to be performed by the
command. Valid entries are 1, 2, 3, 4, 5, 6, 15 and 16.
DevAddress This parameter defines the starting address in the device being
considered by the command. Values entered in this field are dependent
on the node’s database definition. Refer to the specific manufacture’s
database definition for the device to determine the location of the data to
be interfaced.
3.1.4 Status Data
This data area views the status of the module. Use this data to monitor the state
of the module at a "real-time rate". Refer to the MVI46-MCM Status Data
Definition (page 82) for a complete listing of the data stored in this object. This
data can be read from the module’s M1 file starting at register 7200. User data
file N30 is defined in the example ladder logic for this purpose.