HP NuDAQ I-9111DG/HR 4.1.1A/D Conversion Procedure, 4.1.2A/D Signal Source Control, Operation Theorem ∙23, Signal Type & Signal Conditioning

4.1.1A/D Conversion Procedure

For using the A/D converter, users must know about the property of the signal to be measured at first. The users can decide which channels to be used and connect the signals to the PCI-9111. Refer to section 2.7 ‘Connectors Pin Assignment’. In addition, users should define and control the A/D signal sources, including the A/D channel, A/D gain, and A/D signal types. Please refer to section 4.1.2. For A/D signal source control.

After deciding the A/D signal source, the user must decide how to trigger the A/D conversion and define/control the trigger source. The A/D converter will start to convert the signal to a digital value when a trigger signal is rising. Refer to the section 4.1.3 for the three trigger modes.

The A/D data should be transferred into PC's memory for further using or processing. The data can be either read by I/O instruction which is handled directly by software or transferred to memory via interrupt.

Please refer to section 4.1.4 to obtain ideas about the multi -configurations for A/D data transferring.

Some applications need to grab the data only before or after special hardware event. The Pre-Trigger is useful to stop the A/D operation. Refer to section 4.1.5 for operation of pre-trigger mode.

To process A/D data, programmer should know about the A/D data format. Refer to section 4.1.6 for details.

4.1.2A/D Signal Source Control

To control the A/D signal source, the signal type, signal channel and signal range should be considered.

Signal Type & Signal Conditioning

The A/D signal sources of PCI-9111 could be single ended (SE) only. Three are 16 SE A/D channels on board. The R/C filters (attenuators) are on board for every channel. The RC circuit for each channel is shown in the following diagram, where ‘n’ is the channel number. User can install the R, C for special purpose such as attenuating the voltage to increase the input voltage range.

Analog Input	RA n	To Multiplexer
	0 Ohm
Channel #n
	RB n	CA n
	OPEN	OPEN

Operation Theorem ∙23