Rockwell Automation 1771-DB Basic Module User Manual - Series A - Manual (Page 75)

Operating Functions
Chapter 5
5–38
Mode: COMMAND AND/OR RUN
Type: ASSIGNMENT
The arithmetic expression, or expressions, following the PUSH statement
are evaluated and then placed in sequence on the BASIC Module’s
ARGUMENT STACK. This statement, in conjunction with the POP
statement, provides a simple means of passing parameters to assembly
language routines. In addition, the PUSH and POP statements are used to
pass parameters to BASIC subroutines and to “SWAP” variables. The last
value PUSHed onto the ARGUMENT STACK is the first value POPed off
the ARGUMENT STACK.
Variations: You can push more than one expression onto the ARGUMENT
stack with a single PUSH statement. The expressions are followed by a
comma: PUSH[expr],[expr],......... [expr]. The last value PUSHed onto the
ARGUMENT STACK is the last expression [expr] encountered in the
PUSH STATEMENT.
Examples:
SWAPPING CALL
VARIABLES ROUTINE
u10 A=10 u10 PUSH 3
u20 B=20 u20 CALL 10
u30 PRINT A,B u30 POP W
u40 PUSH A,B u40 REM PUSH VALUE ON STACK, CALL
u50 POP A,B u50 REM CONVERSION, POP RESULT IN W
u60 PRINT A,B u60 END
u70 END
uRUN
10 20
20 10
READY
u
5.4.25
Statement: PUSH[expr]