Vernier LabPro User Manual
Page 18
Revision Date: 08/02/02
LabPro Technical Manual
18
12,41,-1,m,n
returns data points starting with point m and ending at point n. Data is position of the
rotary motion sensor, relative to its position when the data collection began.
Digital Outputs
The electrical characteristics of the digital outputs are:
♦
Voutput-high
≥
3.7 V @ -400 uA
♦
Voutput-low
≤
0.65 V @ 1.6 mA
Using Command 2001
This is the simplest way to set the status of the digital output lines. Just send the following command to
LabPro: 2001, X, where X is a number between 0 and 255, that matches the binary pattern you want on the
8 digital output lines. For example, sending 2001, 7 will set the first three digital output lines on
DIG/SONIC1 to high and all the other digital output lines to low.
Port
Bit Value
128
64
32
16
8
4
2
1
DIG/Sonic1
DIG/Sonic2
If you use a series of numbers after the 2001 in the command line, the data will be sent out at about 200-
µ
sec intervals.
Using the Digital Output Buffer
A more complex method of controlling the digital output lines is to use the digital output buffer. This is
especially useful when you want a pattern of outputs to be repeated. Examples include, flashing LEDs or
stepper motors.
The digital output buffer (DOB) is a circular buffer that contains up to 32 elements. The output from the
buffer is 4-bits wide, and the outputs are CMOS (0-5V) compatible. The data in Command 1 is entered as
decimal representation of the digital value that is output. For example, 0=0000, 5=0101, and 15=1111. At
the beginning of each sample, a pointer into the digital output buffer is incremented and the next available
data is sent to the output lines.
The number of times that the DOB outputs the contents of the buffer depends on the number of data
elements defined in Command 1 and the number of samples defined in Command 3.