snap ethernet-based i/o units protocols and programming guide

Bytes 0–3
Bytes 4–7
Bytes 8–11
Bytes 12–15
Binary notation is
shown on the left
side of the window.
The buffer shows the
data that will be sent,
in hex.
Write Quadlet Request Packet (PC➞Brain)
CHAPTER 4: USING THE IEEE 1394-BASED PROTOCOL
The packet constructed by the BuildWriteQuad subroutine appears as follows in binary notation.
(For more information on communication packets, see “Read and Write Packet Structure” on
page 93).
destination_ID tl rt tcode pri
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0
source_ID destination_offset
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
destination_offset
1 1 1 1 0 0 0 0 0 0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
quadlet_data
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
In hex, the packet looks like this:
000004000000FFFFF038000000000001
destination_offset
quadlet_data
OptoEIEIO shows you the correlation between binary and hex in the Write Quadlet Request
dialog box. To see the dialog box, follow these steps:
1. In the OptoEIEIO main window, open the Advanced menu and make sure Auto Parsing is
enabled.
2. Also from the Advanced menu, choose Send Packets Manually.
3. In the Manual Mode dialog box, click Write Quadlet Request, and then click Show Selected
Type.
Hex notation is shown on the right side
of the window.
Enter data on the hex side of the window
for the fields you need to complete. The
binary side changes to match.
To place changed hex values into
the buffer, click this button.
To place buffer values into the hex
fields, click this button.
SNAP Ethernet-Based I/O Units Protocols and Programming Guide 83