
6. NONVOLATILE MEMORY
B–61863E/15
PMC SEQUENCE PROGRAM
366
(4) Nonvolatile memory control (MWRTF, MWRTF2) (Address K16)
This memory is used when the position of a moving part of the
machine tool, such as a lathe turret, is stored in code (BCD, etc.) and
to maintain it while power is off.
#7 #6 #5 #4 #3 #2 #1 #0
K16 MWRTF2 MWRTF
Setting and display are possible from the CRT/MDI panel, and
sequence program instructions can be used for reading and writing.
If, for example, power is turned off for some reason during rotation
of the turret, the turret stops and a difference between the contents of
the memory storing the position and the actual position of the turret
occurs. When power is turned on again, the machine tool will be out
of sequence. To prevent this, use the nonvolatile memory control, and
a sequence program as follows.
(a) Set MWRTF in nonvolatile memory control to 1 before starting
the turret.
(b) Start the turret.
(c) Set MWRTF to 0 after the turret stops.
(d) MWRTF remains 1 if power is turned off between a) and c).
(e) When power is turned on again, automatically MWRTF2 = 1 and
an error is reported to the sequence program. Thus, the sequence
program processes (a) to (d), check for the error of MWRTF2, and
outputs an alarm when MWRTF2 = 1 (error).
(f) In response, the operator should set MWRTF and MWRTF2 to 0
from the CRT/MDI panel.
(g) Resume operation after the contents of the memory and the turret
position are aligned.
(5) Data table
A sizable amount of numeric data (data table) can be used for
sequence control by the PMC. See section 6.3 for details.