Echelon OpenLDV User Manual download pdf (Page 75)

OpenLDV Programmer’s Guide 67

turnaround

If the turnaround bit is set, the message is a turnaround message, that is, a

message sent from one network variable to another network variable on the

same device.

pool

Set the pool bit should 0 for a downlink message.

response

Set the response bit to 1 for a downlink response message, and 0 otherwise. If

it is set for an uplink message, the message is a response to a previously sent

request.

length

The length field in the message header is distinct from the length field in the

application layer header. The length field the message header indicates the

number of bytes for the message data.

Network Address

The network address specifies the address for network (niCOMM) messages,

which includes application messages as well as network variable messages. The

network address is not used for local (niNETMGMT) messages or for implicitly

addressed downlink messages, but it must be present in the application buffer.

The type definition for ExplicitAddr is a union of three structures, depending on

the type of message buffer. For more information about address modes and the

corresponding structures, see the ISO/IEC 14908-1 protocol specification.

The OpenLDV Developer Example also contains an example definition of the

related structures in the OpenLDVdefinitions.h header file.

SendAddrDtl

This structure is used for a downlink, explicitly addressed message, and contains

the destination address of the downlink message in one of four formats,

depending on the address mode. The address modes for sending explicitly

addressed messages are broadcast, group, subnet/node, Neuron ID, local, and

implicit. The SendAddrDtl formats for downlink messages sent using each of

these address modes are displayed below.

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Echelon OpenLDV User Manual Page 75