The object provides the communication with other computers (usually with control computers of
PLC type)
via Ethernet or
via the computer's serial port (
COM1,
COM2, …).
One or more objects
PmaCommMsg or
PmaCommGroup can be created in the
PmaComm object.
This object can be created in objects:
PmaRoot,
PmaFolder,
PmaPrototype. Multiple objects of this type can be created in such objects.
The usage of the
PmaComm object requires purchase of the licence for the appropriate communication driver - see
List of communication drivers.
The
PmaComm object can be used in the application more times, it can be even configured more times with the same protocol (i.e. with the same driver).
For serial link each
PmaComm object must have
defined another communication port. For example, if one
PmaComm object communicates through
COM1, then next
PmaComm object can communicate for example through
COM2 (
COM3, …) but it mustn't communicate through
COM1.
The
PmaComm object specifies what port and protocol will be used for the data transfer. Data required for transmission are then defined in the
PmaCommMsg or
PmaCommGroup nested objects.
PmaCommMsg and PmaCommGroup objects comparison:
- 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).