ProSoft Technology MVI71-MNET - Manual (Page 77)

Reference MVI71-MNET ♦ PLC Platform
User Manual Modbus TCP/IP Interface Module
ProSoft Technology, Inc.
Page 77 of 109
June 23, 2009
1 The client driver obtains configuration data from the MNET.CFG file when the
module restarts. The configuration data obtained includes the timeout
parameters and the Command List. These values are used by the driver to
determine the type of commands to be issued to the other nodes on the
Modbus TCP/IP.
2 After configuration, the client driver begins transmitting read and/or write
commands to the other nodes on the network. If writing data to another node,
the data for the write command is obtained from the module's internal
database to build the command.
3 Presuming successful processing by the node specified in the command, a
response message is received into the client driver for processing.
4 Data received from the node on the network is passed into the module's
internal database, assuming a read command.
5 Status data is returned to the PLC processor for the client and a Command
List error table can be established in the module's internal database.
Client Command List
In order for the client to function, the module's Client Command List must be
defined. This list contains up to 100 individual entries, with each entry containing
the information required to construct a valid command. This includes the
following:
ƒ Command enable mode ((0) disabled, (1) continuous or (2) conditional)
ƒ IP address and service port to connect to on the remote server
ƒ Slave
Node Address
ƒ Command Type - Read or Write up to 100 words per command
ƒ Database Source and Destination Register Address - Determines where data
will be placed and/or obtained
ƒ Count - Select the number of words to be transferred - 1 to 100
ƒ Poll Delay (1/10
th second)