Changing the default state of the counters in the DAQPad-6016 to powerup state of low (0v)

[Ronm]

Hi,

I am using the DAQPads counter for a PWM application in which it is crucial that the default state of the counters will be low (0 volts) on power up.

(The idea is to prevent undesired consequences if the device resets unintentionally)

I read in the forums that this could be accomplished by wiring a resistor between the counter out and the ground.

1. Is this true for the DAQPad-6016?
2. Where can I find The DAQPad-6016 internal diagram?
3. What should be the size of the resistor?
4. Will it affect the way I use the counters?

Thank you,

Ron

[JB]

According to the page 2 of this document, there is a 50k pull-up resistor on a counter output. But on page 3 there is following note : "The tolerance on the 50 kΩ pull-up resistors is large. Actual value might range between 17 kΩ and 100 kΩ."

The formula for the external pull-down resistor is : R = (Uout * Rpu) / (5 - Uout)

with :

• Uout = max acceptable voltage at power up --> eg 0.4V for TTL compatibility
• Rpu = internal pull-up resistor --> 17k to 100k

depending on Rpu and with Uout = 0.4V :

• 100k, R = 8.69k --> 8k1
• 50k, R = 4.34k --> 3k9
• 17k, R = 1.47k --> 1k2

I would start with a 3k9 resistor and then adapt the value if needed to get the expected power-up voltage.

This will have no influence for the use of the counter.