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Commands - 83

ON BIT

Tasking Statement

SYNTAX: ON BIT task numbe r,ad dress, bit GOS UB line/label

PURPOSE: To declare an I/ O line to be m onitored fo r changes in logic level.

REMARK S: Any eight I/O lines may be monitored so that a change in state causes a program branch to the

specified subroutine.

The I/O lines may be located on any parallel port. A change of state is either a low to high or a high

to low transition.

The specified line is sam pled at each tick of the system clock. When the ON BIT statement is

executed, the specified line is sampled for the current state.

The task does not become active until the START BIT statement is executed. The STOP BIT

statement will disable the event.

The BIT task number ranges from 0 to 7. address ranges from 0 to 65, 535. bit ranges from 0 to 7.

line/label may be any valid pr ogram line numbe r or label.

See the Multitasking Chapter for more information.

RELATED: START BIT, STOP BIT

EXAMPLE: 10 ON BIT 0,0,0 GOSUB 60

20 START BIT 0

30 PRINT "waiting..."

40 DELAY .5

50 GOTO 30

60 IF BIT(0,0) = 1 THEN PRINT "closed" ELSE PRINT"open"

70 RETURN

ERROR: < Data negative> – for task, address, bit

< Data out of range> – if bit,task or bit > 7

< Data> 65,535> – for address

< Can’t compile> – if line/label does not exist

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Remote-processing CAMBASIC Manual de usuario Pagina 116