8.3
Modbus Function Codes.......................................................................................................................... 138
Modbus/TCP Client ................................................................................................................... 139
9.1
The Communications Request ............................................................................................................... 139
COMMREQ Function Block ...................................................................................................................................140
COMMREQ Command Block................................................................................................................................140
Modbus/TCP Channel Commands ...................................................................................................................140
Status Data ..................................................................................................................................................................141
9.2
The COMMREQ Function Block ..........................................................................................................................143
The COMMREQ Command Block ......................................................................................................................144
9.3
Modbus/TCP Channel Commands ........................................................................................................ 145
9.4
Status Data ............................................................................................................................................... 161
Types of Status Data ...............................................................................................................................................161
9.5
COMMREQ Ladder Logic Example ...................................................................................................................163
9.6
OPC UA Server ........................................................................................................................... 173
10.1
OPC UA Server Service Request ........................................................................................................................174
OPC UA Server Subroutine ...................................................................................................................................182
Anonymous Authentication.................................................................................................................................187
OPC UA Security Settings ......................................................................................................................................190
OPC UA Address Space ..........................................................................................................................................190
GFK-2224Q
January 2017
Contents
vii