4.4D/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.

-10V

 

Pin- 30 (DA Out)

Ref In

 

D/A Converter

-

To D/A Output

 

+

 

 

 

 

Analog GND

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:

Vout

=

span x DAn / 4096

– Unipolar

Vout

=

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 Vout 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.

Digital Data Input

Analog Output

 

 

Unipolar

Bipolar

 

 

0V ~ 10V

-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

 

 

 

Operation Theorem 33

Page 43
Image 43
HP NuDAQ I-9111DG/HR manual D/A Conversion, 44mV 88mV