Measurement Computing CIO-DAC02/16 - Manual (Page 7)

3.2 SIMULTANEOUS TRANSFER JUMPER
Analog outputs can be jumpered so that new output data for one (or both) DACs is
held in the registers until any register is read. With this jumper in the XFER position,
when any register from BASE +0 to BASE +3
is read, both DACs are updated simultaneously
with data TRANSFERRED from the four
registers.
Figure 3-2 to the right shows the jumper block
in the individual UPDATE (default) position.
Figure 3-2. Simultaneous Transfer Jumper
Simultaneous transfer is useful if a system requires that a zero voltage be applied from
the CIO-DAC02/16 outputs at power up and reset.
The CIO-DAC02/16 outputs are set to 0 volts at power-up and reset but the data in the
data registers is not necessarily zero. To avoid a random value being output, use
simultaneous update mode and initialize all registers with appropriate values before
updating any channel.
3.3 VOLTAGE RANGE SWITCHES
The D/A converters on the CIO-DAC02/16 output a voltage according to the
equation:
Unipolar
Volts Out = (V
FS
/ 65536 ) x Digital Value
Bipolar
Volts Out = (V
FS
/ 65536 ) x Digital Value
−
( 0.5 x V
FS
)
For example, in the 0 to 10V range with an output value of 50350:
Volts Out = (10/65536) * 50350 = 7.6828 volts
Two banks of DIP switches located upper left and right on the CIO-DAC02/16 are
used to set the voltage output range of the two DACs. The range of each DACs is set
according to the following switch settings Figure . Holding the board as it would sit in
the computer expansion slot, U means switch is UP, D means switch is DOWN.
3
XFER UPDATE
JUMPER BLOCK - The jumper block
is in the Individual-Update position.