B&B Electronics RS-232 Digital I/O Module 232SDD16 - Manual (Page 14)

232SDD16-1005 Manual 23
B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350
PH (815) 433-5100 -- FAX (815) 433-5104
Step 5 - Determining the I/O line definitions:
MSdefs = MSdefs AND mask
LSdefs = LSdefs AND mask
By "ANDing" the value of MSdefs or LSdefs with the appropriate
mask of an I/O line, the I/O line definition can be determined. If
the status is equal to zero the I/O line is an INPUT. If the status is
not equal to zero the I/O line is an OUTPUT. Table 5.1 shows
the mask values for each I/O line.
Step 6 - Repeat Step 5 until the status of each I/O line has been
determined.
Step 7 - Determining an OUTPUT's Power-up state:
MSpups = MSpups AND mask
LSpups = LSpups AND mask
By "ANDing" the value of MSpups or LSpups with the
appropriate mask of an Output line, the Output line definition can
be determined. If the status is equal to zero the Output power-up
state will be LOW. If the status is not equal to zero the Output
power-up state will be HIGH. Table 5.1 shows the mask values
for each I/O line.
Step 8 - Repeat Step 7 until the power-up state of each Output line
has been determined.
Example 5.2 - Determining the definition and power-up state of I/O
lines #2 & #10
mask = &H4
Cmnd$ = "!0RC"
PRINT #1, Cmnd$;
MSdefs$ = INPUT$(1,#1)
LSdefs$ = INPUT$(1,#1)
MSpups$ = INPUT$(1,#1)
LSpups$ = INPUT$(1,#1)
MSdefs = ASC(MSdefs$)
LSdefs = ASC(LSdefs$)
MSpups = ASC(MSpups$)
LSpups = ASC(LSpups$)
MSdefs = MSdefs AND mask
LSdefs = LSdefs AND mask
MSpups = MSpups AND mask
LSpups = LSpups AND mask
24 232SDD16-1005 Manual
B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350
PH (815) 433-5100 -- FAX (815) 433-5104
If LSdefs equals zero then I/O line #2 is an INPUT and if not equal
to zero then I/O line #2 is an OUTPUT. If MSdefs equals zero then
I/O line #10 is an INPUT and if not equal to zero then I/O line #10 is
an OUTPUT. If LSpups equals zero then Output line #2's power-up
state is LOW and if not equal to zero then Output line #2's power-up
state is HIGH. If MSpups equals zero then Output line #10's power-
up state is LOW and if not equal to zero then Output line #10's
power-up state is HIGH.
Set Output States Command
Step 1a - Construct the command string:
Set appropriate outputs HIGH
MSstates = MSstates OR mask
LSstates = LSstates OR mask
By "ORing" the current states with the appropriate mask of a
digital output line, the output's bit will be set to a "1" (HIGH).
Step 1b - Set appropriate outputs LOW
MSstates = MSstates AND (NOT(mask))
LSstates = LSstates AND (NOT(mask))
By "ANDing" the current states with the complement of the
appropriate mask of a digital output line, the output's bit will be
set to a "0" (LOW).
Step 1c - Completing the command string:
Cmnd$ = "!0SO" + CHR$(MSstates) + CHR$(LSstates)
Step 2 - Transmitting the command string:
Print #1, Cmnd$;
Example 5.3 - Set Output #0 HIGH and Output #14 LOW.
'Set bit 0 of LSstates to make Output #0 HIGH.
LSstates = LSstates OR &H1
'Clear bit 4 of MSstates to make Output #14 LOW.
MSstates = MSstates AND (NOT(&H40))
Cmnd$ = "!0SO" + CHR$(MSstates) + CHR$(LSstates)
PRINT #1, Cmnd$;
MSIO$ = INPUT$(1,#1)
Output #0 will be set HIGH and output #14 will be set LOW. All
other output setting will not be changed.