User's Manual

Documentation Number 232OPSDA1397 Manual 23
B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350
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‘ Open the serial port.
‘
OPEN “COM1:9600,N,8,1,cd,ds” FOR RANDOM AS #1
PAUSE (.5)
‘ Close the serial port when finished.
‘
CLOSE #1
Read A/D Command
The read A/D channels command returns two bytes of data for
each channel read. The two bytes represent the most significant
byte (MSB) and least significant byte (LSB) of the reading. The MSB
is received first, followed by the LSB. This command requires a data
byte. The data byte is used to specify the number of the highest
channel to be read. All channels less than this channel will be read
as well.
Step 1 - Constructing the command string:
Command$ = “!0RA” + CHR$(channel)
The value of channel is equal to the highest channel to be read.
Step 2 - Transmitting the command string:
Print #1, Command$;
Step 3 - Receiving the data:
MSB$ = INPUT$(1, #1)
LSB$ = INPUT$(1, #1)
Step 4 - Manipulating the data:
reading = (ASC(MSB$) * 256) + ASC(LSB$)
The value of reading is the result of the A/D conversion.