4. Configuration
40
VAR RETAIN
wLocalSymbolicRetentiveVariable_01 : WORD;
END_VAR
Or, for global variables, declared within a list of global variables:
VAR_GLOBAL RETAIN
wGlobalSymbolicRetentiveVariable_01 : WORD;
END_VAR
On the other hand, the persistent symbolic variables shall be declared in a Persistent Variables object,
being added to the application. These variables will be global and will be declared in the following
way within the object:
VAR_GLOBAL PERSISTENT RETAIN
wGlobalSymbolicPersistentVariable_01 : WORD;
END_VAR
As of versions 1.5.0.22 for NX3004 and 1.5.1.1 for NX3010, NX3020 and NX3030, the Nexto series
CPUs allow flexibility on the usage of retentive and persistent memories. This means that the user
will be able to choose the size that will be used for each type of memory, as long as the retentive and
persistent memory sum don’t exceed the total limit available in each CPU model. The total of
retentive and persistent memory available is described in Table 2-5 in Specific Features.
If the retentive symbolic, persistent symbolic, retentive %Q and persistent %Q memory sum exceed
the total available, MasterTool will show an error during the code generation.
If, for example, an NX3004 CPU that has 7680 Bytes of retentive and persistent memory is used and
it’s configured 1000 retentive Bytes and 1000 directly addressable (%Q) output Bytes and, still, the
variables in the code below are declared, the total retentive and persistent memory used is going to be
2004 Bytes, leaving 5676 Bytes for free usage.
VAR_GLOBAL PERSISTENT RETAIN
wVariavelSimbolicaPersistenteGlobal_01 : WORD;
END_VAR
VAR_GLOBAL RETAIN
wVariavelSimbolicaRetentivaGlobal_01 : WORD;
END_VAR
ATTENTION:
To use the retentive and persistent memory flexibly, it’s necessary to use MasterTool IEC XE 2.03
or higher.
TCP Configurations
Some of the advanced configurations affect the Nexto Series CPUs supported protocols, as they are
connected to the TCP network layer, as following:
ï‚· Initial Time-out
ï‚· ACK Delay
The CPU Nexto, before it responds to any request and as any other Ethernet equipment which uses
the TCP transport layer, demands a communication door opening, in other words, the connection
establishment.
The Interface connections quantity is limited and simply does not establish any other connection after
its limit is reached. This can cause problems for the established connections in the server mode, as
the connections closing depends on the other equipment, the client.
The TCP transport layer, responsible for the messages deliver from the origin to destiny, has some
parameters with time-outs, very common in general communication protocols. Such parameters are
intended to recover the communication after the failures are determined. The user must be aware with
the time-outs configuration, as it some conflicts might occur with the values configured inside the
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General