Echelon OpenLDV User Manual download pdf (Page 86)

78 Sending and Receiving Messages with the OpenLDV API

enumeration type definition NI_QueueCmd used in the field NI_Hdr.q.q_cmd of

the application layer header, and the queue codes are defined by the enumeration

type definition NI_Queue used in the field NI_Hdr.q.queue. The OpenLDV

Developer Example contains a utility function, COpenLDVni::msgHdrInit(),

that computes the correct value for the command/queue byte based on the

address type (local or remote), the service type, and the priority attribute of the

message.

Literals for the supported immediate commands are defined in the OpenLDV

Developer Example by the enumeration type definition NI_NoQueueCmd used

in the field NI_Hdr.q of the application layer header.

Table 33. Network Interface Commands

Network Interface

Command Value Direction Description

niL2_INCOMING 0x1A Uplink Specifies a Layer 2 incoming

packet.

niL2_INC_M1 0x1B Uplink Specifies a Layer 2 Mode 1

incoming packet.

niL2_INC_M2 0x1C Uplink Specifies a Layer 2 Mode 2

incoming packet.

niCOMM + niTQ 0x12 Downlink Used for downlink non-priority

messages using acknowledged,

request and repeated services. For

Layer 2 devices, also used for

unacknowledged messages.

This command specifies niCOMM

(for messages sent to and received

from the network) as the queue

value and niTQ as the command

value.

Applies to Layer 2 or Layer 5

devices. The command format is

different for Layer 2 and Layer 5.

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Echelon OpenLDV User Manual Page 86