DLN_MSG_HEADER

The message header is the first field of each message, sent from a host to a device or vice versa. It is used to identify and route the message correctly.

The DLN_MSG_HEADER structure is used to describe a message (command, response or event).

Syntax

C/C++
 typedef struct {
    uint16_t size;
    uint16_t msgId;
    uint16_t echoCounter;
    HDLN handle;
} __PACKED_ATTR DLN_MSG_HEADER;

Members:

size
Defines the size of the message.
msgId
The message ID, defining the message.
echoCounter
If case of a command/response pair the echo counter is used to establish a one-one link between them. In case the message is an event, this is a free-running counter. It shows the number of events sent by the device. The counter is reset when its value reaches 0xFFFF (65536).
handle
A handle to the DLN-series adapter. In case of an event, it contains the handle of the device, that generated the event. For a command, the handle is defined by a user in order to route it to a specific device. The HDLN_ALL_DEVICES constant can be used to send the command to all devices.