Yaskawa SMC–4000 - Manual (Page 308)

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SMC–4000 User Manual
Executing Programs - Multitasking
Two programs can run independently. The programs (threads) are numbered 0 through 7. 0 is the main
thread. The main thread differs from the others in the following points:
1. Only the main thread may use the input command, IN.
2. In a case of interrupts, due to inputs, limit switches, position errors or command errors, it is thread 0
which jumps to those subroutines.
The execution of the various programs is done with the instruction:
XQ #A, n
Where n indicates the thread number. To halt the execution of any thread, use the instruction
HX n
where n is the thread number.
Note that both the XQ (Execute Program) and HX (Halt Execution) functions can be performed by an
executing program.
Multitasking is useful for executing independent operations such as PLC functions that occur
independently of motion. The example below produces a waveform on Output 1 independent of a move.
The program above is executed with the instruction XQ #TASK2,0 which designates TASK2 as the main
thread. #TASK1 is executed within TASK2.
#TASK1 Task1 label
AT0 Initialize reference time
CB1 Clear Output 1
#LOOP1 Loop1 label
AT 10 Wait 10 msec from reference time
SB1 Set Output 1
AT -40 Wait 40 msec from reference time, then
initialize reference
CB1 Clear Output 1
JP #LOOP1 Repeat Loop1
#TASK2 Task2 label
XQ #TASK1,1 Execute Task1
#LOOP2 Loop2 label
PR 1000 Define relative distance
BGX Begin motion
AMX After motion done
WT 10 Wait 10 msec
JP #LOOP2,@IN[2]=1 Repeat motion unless Input 2 is low
HX Halt all tasks