PmaCommMsg - Deatiled object description
See: The
PmaCommMsg object
The object is created by the type of the communication protocol set in the
PmaComm object. That's why it is advisable to create the
PmaCommMsg object after the configuration of the
PmaComm object.
The object contains two groups of variables. One serves for the specification of the
sending data (see the "
Data-sent" tab) and the other serves as
receiving data from the communication (see the "
Data-received" tab).
It is possible to access these variables even in the script (see
WriteVars method and
ReadVars method). For example:
- writing into the first (zero-based index) variable for sending data:
- reading the third (zero-based index) variable for receiving data:
#rcvvars and #sndvars identifiers:
In the
PmaCommMsg object, the
#rcvvars and
#sndvars identificators are used for accessing the variables (of the
PmVar type) defined on the
Data-received and
Data-sent tabs. This identifier can be used e.g. in the
Pm method, or in the "
PP - Data binding to Pma object property" data binding. For example the
Pm("/Comm/Msg1/#rcvvars/aaa") method returns the received variable
aaa from the object named "
Msg1" that is of the
PmaCommMsg type.
PmaCommMsg and PmaCommGroup objects comparation:
- The
PmaCommMsg object:
- Is a "low level" object, meaning that the data format in this object is created depending on the communication message type, defined by corresponding protocol. If you want to receive, for example, both registers and counters, then two
PmaCommMsg objects must be created because the current protocol does not support reading both registers and counters in one message.
- The
PmaCommGroup object:
- Compared to the
PmaCommMsg object, it is on a higher level, because the data in this object are not depending on used protocol. It is possible, for example, to define data for both counters and registers and the object will intelligently assemble this data into communication messages.
- Can be used for following drivers:
PmOpcUaClient,
PmModbusMr,
PmS7,
PmSBUS,
PmMBus,
PmKNX,
PmIEC8705,
PmMelsecQA,
PmMelsecFXS,
PmABradleyDF1,
PmFatek and
PmTeco.
For some drivers the
PmaCommGroup object cannot be used based on the principles (e.g. for the
PmChar communication driver, because this user defined protocol does not have any general addressing and depends only on the user, what kind of message will be created by the
PmaCommMsg object).