266 ● ZS DMC-40x0 Command Reference
ZS
FUNCTION: Zero Subroutine Stack
DESCRIPTION:
The ZS command is only valid in an application program and is used to avoid returning from an
interrupt (either input or error). ZS alone returns the stack to its original condition. ZS1
adjusts the stack to eliminate one return. This turns the jump to subroutine into a jump. Do
not use RI (Return from Interrupt) when using ZS. To re-enable interrupts, you must use II
command again.
The status of the stack can be interrogated with the operand _ZSn - see operand usage below.
ARGUMENTS: ZS n where
n = 0 Returns stack to original condition
n = 1 Eliminates one return on stack
USAGE: DEFAULTS:
While Moving Yes Default Value 0
In a Program Yes Default Format 3.0
Command Line No
Controller Usage
ALL CONTROLLERS
OPERAND USAGE:
_ZSn contains the stack level for the specified thread where n = 0 to 7.
EXAMPLES:
#A ;'Main Program
II1 ;'Input Interrupt on 1
#B;JP #B;EN ;'Loop
#ININT ;'Input Interrupt
MG "INTERRUPT" ;'Print message
S=_ZS ;'Interrogate stack
S=
;'Print stack
ZS ;'Zero stack
S=_ZS ;'Interrogate stack
S=
;'Print stack
EN ;'End
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