User's Manual

24 485SDA103798 Manual
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Table 5.1 - Digital I/O Mask Values
Example 5.2 - Determining the status of Digital Input #1 of the
module with and address of 10.
mask = &H10
Command$ = “!” + CHR$(addr) + “RD”
Print #1, Command$;
Reply$ = INPUT$ (1, #1)
states = ASC (Reply$)
status = states AND mask
If status is equal to zero then Digital Input #1 is LOW. If status is
not equal to zero then Digital Input #1 is HIGH.
Set Digital Output States
The Set Digital Output command is used to set the states of the
3 digital output lines. This command requires a data byte. The data
byte is used to specify the output states. Bits 0-2 correspond to the
states of digital outputs 0-2. If a bit is a 0 then the output will be set
LOW. If a bit is a 1 then the output will be set HIGH. NOTE: This
command ignores Bits 3-7 of the data byte.
The steps to setting the digital output states are given below:
1) Constructing the command string:
a) Set Appropriate Outputs HIGH
states = states OR mask
By “ORing” the current states with the appropriate
mask of a digital output (given in Table 5.1), the
output’s data bit will be set to a “1” (which will be set
HIGH).
Mask Values
I/O Line Hexadecimal Decimal
Digital Output #0 1H 1
Digital Output #1 2H 2
Digital Output #2 4H 4
Digital Input #0 8H 8
Digital Input #1 10H 16
Digital Input #2 20H 32