User`s guide

Operation Theorem •33
4.4 D/A Conversion
The PCI-9111 has one analog output channel. The signal range can be
uni-polar or bi-polar which are set by JP1.
To D/A Output
D/A Converter
-
+
-10V
Ref In
Analog GND
Pin-30 (DA Out)
The operation of D/A conversion is simpler than A/D operation. You only
need to write digital values into the D/A data registers and the
corresponding voltage will be output from the DA Out (pin-30 of CN3).
Refer to section 3.15 for information about the D/A data registers. The
mathematical relationship between the digital data DAn and the output
voltage is formulated as following:
V
out
= span x DAn / 4096 – Unipolar
V
out
= span x DAn / 4096 + (-10) – Bipolar
where span is the span in volts. If your output range is -10V~10V (Bipolar),
then span is 20; if your output range is 0~10V (Unipolar), then span is 10.
The V
out
is the output voltage, and the DAn is the digital data value in the
D/A data registers.
Before performing the D/A conversion, users should care about the D/A
output range which is set by the JP1. Please refer section 2.4 for jumper
setting.
Analog Output
Digital Data Input
Unipolar
0V ~ 10V
Bipolar
-10V ~ 10V
FFF hex +9.9976V +9.9951V
800 hex +5.0000V 0.0000V
7FF hex +4.9976V -0.0049V
000 hex 0.0000V -10.0000V
1 LSB 2.44mV 4.88mV