pinout 1.5 V DC AAA battery voltage measurement with DAQ USB 6009

[feanorou]

Hello, I have a very basic question with pinout when measuring 1.5 V voltage on a USB DAQ 6009, using a standard AAA battery. Is it correct to connect (+) to AI0 and (-) to AI4 as suggested in MAX?

Nothing else required?

(pinout attached)

Thank you

[MilanR · Accepted solution]

Hi feanorou,

Yes, when you have the terminal configuration set as Differential, then using the AI 0 pin as (AI 0+) and using the AI 4 pin as (AI 0-) is a good configuration to measure from the AAA battery.

[feanorou]

Hello, I have another question before connecting the battery, how much is allowed current flowing into USB 6009?

Should I use an external resistor to keep current below 8.5 mA?

From the manual I see following:

The default configuration of the NI USB-6008/6009 DIO ports is open collector, allowing 5 V operation, with an onboard 4.7 kΩ pull-up resistor.
An external user-provided pull-up resistor can be added to increase the source current drive up to a 8.5 mA limit per line as shown in Figure 15.

Thank you

[MilanR]

Hi feanorou,

Above you mentioned that you were performing an analog measurement of the battery. As listed in the manual, analog input has 144 kOhms of input impedance so the current created by a 1.5V differential from a battery should not cause any problems!