ProSoft Technology PLX8X-MNET-61850 - Manual (Page 46)

ProSoft 61850 Configuration Manager PLX8x-MNET-61850 ♦ Communication Gateway
User Manual Modbus TCP/IP to IEC 61850
Page 46 of 228 ProSoft Technology, Inc.
May 14, 2014
2.4 Modbus TCP/IP Configuration
2.4.1 Modbus TCP/IP Client Commands Overview
The Modbus TCP/IP Client driver uses a command list to define interactions
between the ProSoft gateway and Modbus TCP/IP server devices. 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 with which to interface,
and the registers in the tag database to be associated with the command. The
Client command list supports up to 1,000 commands.
The command list is processed from top (item #1 in the MODBUS Mapping Tool
window) to bottom. A poll interval parameter is associated with each command to
specify a minimum delay time in tenths of a second between successive
issuances of each particular command. If a value of 10 is specified for the
parameter, the command will be executed no more frequently than once every
second.
Write commands have a special feature; they can be set to execute only if the
data in the data area associated with the write command changes. If the register
data values in the data area associated with the command have not changed
since the command was last issued, the command will not be re-executed until
after a data change has happened. If the data in the command has changed
since the command was last issued, the command will be executed again to
send the new data. Use of this feature can reduce network traffic. In order to
implement this feature, the enable code for the write command will need to be set
to E
NABLE
–
O N D ATA C HANGE .