Vernier LabPro - Manual (Page 68)

Revision Date: 08/02/02
LabPro Technical Manual 68
Command 401 Analog Output Setup
This command sets up parameters to control the analog output driver in LabPro. The output voltage range
is +/- 3 V with a current limit of 100 mA. The output voltage is determined by:
V
out
= 0.0024*amplitude – 0.0012*offset where the result must satisfy –3V < Vout < 3V
The analog output is present on line 1 of CH4. Therefore the Voltage clips supplied with LabPro may be
used to connect the analog output to external circuits. Since this analog out shares the CH4 V
IN
pin, you
may monitor the output voltage by using the {1,4,2} command. You may also monitor the current by
assigning mode 22 to any other unused channel i.e. {1,3,22}.
Once the channel has been setup, the output is enabled immediately regardless of data collection mode. It
will remain active until the unit is reset or until it is disabled using Command 401(reset turns off output in
operating system later than 6.06211).
Using Command 401, the program is able to choose a waveform, amplitude, offset and period and the
analog output will generate the desired waveform. Waveforms other than DC values are divided into steps
of discrete values. The Square wave uses 2 steps per period. The Triangle wave uses 32 steps per period
(16 steps up, 16 steps down). The Ramp Up, Ramp Down, and Sine waveforms also use 32 steps per
period.
Notes about waveforms:
Only OFF and DC waveforms are operational in operating system version 6.06211 or earlier.
The amplitude parameter for sine waves is set to 4V (8Vpk-pk). The amplitude parameter may be used to
indicate how many times to reduce this value in half. See examples for clarification.