B&B Electronics 232SDD16 manual MSdefs = MSdefs and mask LSdefs = LSdefs and mask

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

232SDD16-1005 Manual 23

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.

24 232SDD16-1005 Manual

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