User manual

Chapter 3
VMEbus Interface
3-9
The structure of the command block is shown below:
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0Word
Command word
Response word
Cmd interrupt level
Command interrupt status/ID
Command dependent
0
1
2
3
4
15
Word
Command Description
0 Command word Specifies the type of command and implicitly specifies whether there is an associated command packet.
1 Response word The sender should set this to 0. PLC-5/VME processor stores a nonzero value in this word when
completion of command processing occurs. The value 00FF de-notes successful completion. Other
values are used for errors.
2 Command interrupt
level
If nonzero, specifies that PLC-5/VME processor should generate a VMEbus interrupt immediately after
storing into the response word after command completion.
000 specifies no interrupt,
001 specifies interrupt level 1,
010 specifies level 2,
...,
111 specifies level 7.
3 Command interrupt
status/ID
The status/ID value returned during an interrupt-acknowledge cycle for the above interrupt.