B–64113EN–1/01
15. PMC CONTROL FUNCTION
991
When the execution of command [1] is completed:
⋅ command [2] is transferred from the waiting buffer to the executing
buffer;
⋅ command [3] is transferred from the input buffer to the waiting buffer;
and
⋅ command [4] is transferred to the input buffer as the command block
(axis control block data signal).
After the reception of command [4] by the input buffer, the PMC can issue
command [5] to the CNC (the axis control block data signal is set).
The timing chart for the command operation is shown below.
Command block
(Input)
EBUFg
(Input)
(1) (2) (3) (4) (5)
EBSYg
(Output)
The buffer is full.
Input buffer
[3] [4]
Waiting buffer [2] [3]
Executing
buffer
[1]
Beginning of execution
End of
execution
[1] [2] [3] [4] [5]
[2]
Beginning of execution
(1), (2), (3), (4), (5) : A new block cannot be issued during these
intervals (while EBUFg and EBSYg are in different logical states).
D The status of the CNC buffer can be determined by the exclusive OR
of the axis control command read signal EBUFg, input from the PMC,
and axis control command read completion signal EBSYg, output
from the CNC.
EBUFg
ø
EBSYg
Exclusive
OR
(XOR)
CNC buffer status
01
øø
01
0
The previous block has already been read into the
CNC buffer. The PMC can issue the next block.
01
øø
10
1
The previous block has not yet been read com-
pletely. It is just being read or waiting for the CNC
buffer to become available. Do not issue the next
block, nor reverse the logical state of EBUFg. Re-
versing the EBUFg state invalidates any block that
has been already issued.