B&B Electronics RS-485 Digital I/O Module 485SDD16 - Manual (Page 15)

485SDD16-1005 Manual 25
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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$ = "!" + CHR$(Maddr) + "SO" + CHR$(MSstates) +
CHR$(LSstates)
Step 2 - Transmitting the command string:
Print #1, Cmnd$;
Example 5.3 - Set Output #0 HIGH and Output #14 LOW of module
#5.
'Set module address.
Maddr = 5
'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$ = "!" + CHR$(Maddr) + "SO" + CHR$(MSstates) +
CHR$(LSstates)
PRINT #1, Cmnd$;
Output #0 will be set HIGH and output #14 will be set LOW of
module #5. All other output settings of module #5 will not be
changed.
Define I/O Lines Command
The Define I/O Lines command is used to define each of the
module's I/O lines as either an input or an output. This command
requires two data bytes. Refer to this command in Chapter 3 for
more information.
Step 1a - Construct the command string:
Define an I/O line as Output
MSdefs = MSdefs OR mask
LSdefs = LSdefs OR mask
By "ORing" the current definitions with the appropriate I/O line
mask, the I/O line's data bit will be set to a "1" (HIGH) and the I/O
line will be defined as an Output.
26 485SDD16-1005 Manual
B&B Electronics -- 707 Dayton Road -- Ottawa, IL 61350
PH (815) 433-5100 -- FAX (815) 433-5104
Step 1b - Define an I/O line as an Input
MSdefs = MSdefs AND (NOT(mask))
LSdefs = LSdefs AND (NOT(mask))
By "ANDing" the current definitions with the complement of the
appropriate I/O line mask the I/O line's data bit will be set to a "0"
(LOW) and the I/O line will be defined as an Input.
Step 1c - Completing the command string:
Cmnd$ = "!" + CHR$(Maddr) + "SD" + CHR$(MSdefs) +
CHR$(LSdefs)
Step 2 - Transmitting the command string:
Print #1, Cmnd$;
Example 5.4 - Define I/O line #7 as an Output (HIGH) and I/O line #8
as an input (LOW) on module #4.
'Set module's address to 4.
Maddr = 4
'Set bit 7 of LSdefs to make I/O line #7 an Output (HIGH).
LSdefs = LSdefs OR &H80
'Clear bit 0 of MSdefs to make I/O line #8 an Input (LOW).
MSdefs = MSdefs AND (NOT(&H1))
Cmnd$ = "!" + CHR$(Maddr) + "SD" + CHR$(MSdefs) +
CHR$(LSdefs)
PRINT #1, Cmnd$;
MSIO$ = INPUT$(1,#1)
I/O #7 will be defined as an Output (HIGH) and I/O line #8 will be
defined as an Input (LOW) of module #4. All other I/O definitions will
not be changed.
Set Power-up States Command
The Set Power-up States command is used to set the states of
the digital outputs at power-up. This command requires two data
bytes. Refer to this command in Chapter 3 for more information.
Step 1a - Construct the command string:
Set appropriate outputs power-up states HIGH
MSpups = MSpups OR mask
LSpups = LSpups OR mask
By "ORing" the current power-up states with the appropriate mask
of a digital output line, the power-up state's data bit will be set to a
"1" (HIGH).