Comm¶
All applications have to have some kind of outer blcok.
Globals¶
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comm.client_map¶ This is ...
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comm.server_map¶ This is ...
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comm.service_map¶ This is ...
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comm.element_map¶ This is ...
Functions¶
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comm.bind(*args)¶ Parameters: args – a list of clients and servers to bind together in a stack
Protocol Data Units¶
A Protocol Data Unit (PDU) is the name for a collection of information that is passed between two entities. It is composed of Protcol Control Information (PCI), which usually has information about addressing and other types of processing instructions, and data. The set of classes in this module are not specific to BACnet.
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class
comm.PCI¶ -
pduSouce¶ The source of a PDU. The datatype and composition of the address is dependent on the client/server relationship and protocol context. The source may be None, in which case it has no source or the source is implicit.
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pduDestination¶ The destination of a PDU. The datatype and composition of the address is dependent on the client/server relationship and protocol context. The destination may be None, in which case it has no destination or the destination is implicit.
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__init__([source=addr][,destination=addr])¶ Parameters: - source (addr) – the initial source value
- destination (addr) – the initial destination value
Protocol Control Information is generally the context information and/or other types of processing instructions.
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class
comm.PDUData¶ -
pduData¶ This attribute typically holds a simple octet string, but for higher layers of a protocol stack it may contain more abstract pieces or components.
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get()¶ Extract a single octet from the front of the data. If the octet string is empty this will raise a DecodingError.
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get_data(len)¶ Parameters: len (integer) – the number of octets to extract off the front Extract a number of octets from the front of the data. If there are not at least len octets this will raise a DecodingError exception.
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get_short()¶
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get_long()¶
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put(ch)¶ Parameters: ch (octet) – the octet to append to the end
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put_data(data)¶ Parameters: data (string) – the octet string to append to the end
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put_short(n)¶
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put_long(n)¶
The PDUData class has functions for gathering information from the front of the octet string, or putting information on the end. These are helper functions but may not be applicable for higher layer protocols which may be passing significantly more complex data.
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class
comm.PDU(PCI, PDUData)¶ The PDU class combines the PCI and PDUData classes together into one object.