ALTUS Nexto Series User Manual

5. CONFIGURATION
right read only by the SCADA. When the value of the variable is TRUE, data is read by connecting with this PLC. This way,
every time there is a status change among PLCs, the variable state will also change, remaining in the state TRUE in the PLC
which is in the redundancy active state.
The NonSkippedPrg program code, in ST language, is as follow:
PROGRAM NonSkippedPrg
VAR
{attribute 'symbol' := 'read'}
OPCRedundancyActive : BOOL;
END_VAR
IF fbRedundancyManagement.m_fbDiagnosticsLocal.eRedState = REDUNDANCY_STATE.
ACTIVE THEN
OPCRedundancyActive := TRUE;
ELSE
OPCRedundancyActive := FALSE;
END_IF
The NonSkippedPrg program code can be edited as long as the user watch out not to change the above code. This code
tests the state of redundancy and writes a BOOL type variable called OPCRedundancyActive with it. If the PLC is the active,
the variable value is TRUE, otherwise it’s FALSE. This variable receives the attribute attribute ‘symbol’ := ‘read’ to allow the
OPC DA Server to access the content and define where the information should be read.
If it’s decided to add OPC communication after the creation of the project, it is possible to configure the OPC by adding
the above code in the NonSkippedPrg program and adding the Symbol Configuration object to the project.
For the configuration of the redundant PLC on the OPC DA Server, it’s necessary to enable the Redundancy Configuration
option in the configuration screen as shown in Figure 88. When this option is selected, the option Use TCP/IP Blockdriver will
always be used. In addition, the IP Address PLC A and IP Address PLC B fields will be enabled as described in Table 128.
These IP Addresses are configured in the same Ethernet interfaces within the PLC project with Half-Cluster redundancy. For
ease of configuration when a redundant project is open, the Read Project Configuration button can be used.
ATTENTION
The OPC DA Server connection redundancy is done through only one Server. For the cases
in which a better data availability for the supervision systems is desired, a redundant SCADA
Server architecture must be adopted. In this cases it isn’t required any OPC DA Server
configuration. Refer to the SCADA system documentations to see which configurations are
needed for the operation of the redundant architecture.
5.5.10.4. OPC DA Communication Status and Quality Variables
For each PLC created in the OPC DA Server, status variables are generated, named _CommState and _CommStateOK. The
_CommState variable indicates the communication between the OPC and the PLC state. This state can interpreted by the OPC
Clients according to table below.
State Value Description
STATE_TERMINATE -1
If the communication between the OPC DA Server and
the OPC Client is terminated, this value will be returned.
When there’s more than one OPC Client simultaneously
connected, this return will occur on the disconnection of
the latter connected one. Besides the fact that this state
is in the variable, it’s value can’t be visualized because
it only changes when there’s no longer a connection with
the client.
160

ALTUS Nexto Series Specifications

General

Brand	ALTUS
Model	Nexto Series
Category	Computer Hardware
Language	English