
B–63523EN–1/03
15. PMC CONTROL FUNCTION
1841
A program number (1 to 9999) is specified from an extended source and
is selected in the CNC memory.
For machines that can load several kinds of workpieces, this function can
automatically select the program to be executed corresponding to a
specific workpiece.
Data for the external program number search is accepted regardless of
CNC mode, but the search execution can be made only in the reset state
in MEM mode.
The ESEND signal switches from “0” to “1” on completion of external
program number search. This signal does not turn to “0” unless the cycle
start or reset signal is input, or another search is made. Use ESEND to
initiate a cycle start signal after the search.
Because a search operation is deferred until a reset occurs in the MEM
mode, an external program number search attempted during a CNC
operation (OP = 1) results in the program being started immediately after
the end of an automatic operation in a sequence in which the automatic
operation is started by checking only the ESEND signal (search
completion signal for external data input). For this reason, using the ESC
parameter (bit 3 of parameter No. 6300) enables an external program
number search to be canceled at a CNC reset. Concretely, if a reset signal
is input between the time the ESTB signal (read signal for external data
input) is input and the time a search would be executed, setting the ESC
parameter (bit 3 of parameter No. 6300) to 1 keeps the search from being
executed. At the same time, the controller uses the ESCAN (search cancel
signal for external data input) signal to inform the PMC that the search
has been canceled. The ESEND signal (search completion signal for
external data input) will not become 1, because the search is canceled.
The controller checks the state of the RST (NC reset) signal for a reset
input between the rising edge of the ESTB signal (read signal for external
data input) and the start of the search. Concretely, the controller cancels
the external program number search if the RST (NC reset) signal becomes
1 even momentarily in this period. The ESCAN signal (search cancel
signal for external data input) becomes high at the beginning of the search.
However, it becomes low when the next search is executed (for example,
when a cycle start or reset signal is input), similarly to the ESEND signal
(search completion signal for external data input).
1) External Program
Number Search