V2 and 12v input

[kbracing96]

I have a Devils Own Alcohol injection system on my truck that uses a micro proceser and PWM to progressively control the speed of the pump based on the MAP voltage. Could I set up my V2 to log this though one of the 12v input to show me when and how fast the pump is running at a given time in the log?

[kbracing96]

Ok, so I put this in the wrong section. Joecar, can you help me out with that. And anyone have any ideas on it???

[TAQuickness]

If it's a progressive 12vdc, probably not. My understanding is the 12vdc inputs are on off only.

[joecar]

Ok, so I put this in the wrong section. Joecar, can you help me out with that. And anyone have any ideas on it???Kb,

This is the right section, I think everyone's response has slowed down, something to do with eggnog consumption... ;)

I believe the 12V inputs detect discreet "high" and "low" and not continuous analog voltage.

I'll pm Paul, he will have a definitive answer.

Cheers,
Joe

[kbracing96]

Kb,

This is the right section, I think everyone's response has slowed down, something to do with eggnog consumption... ;)

I believe the 12V inputs detect discreet "high" and "low" and not continuous analog voltage.

I'll pm Paul, he will have a definitive answer.

Cheers,
Joe

Well, I though after I posted it here and then went back to the main page and saw the external A/D input section that I had put it in the wrong section.

Anyway, I was thinking that since it's PWM control which is basically turning it on and off really fast, that I might be able to log it thought the 12v input, but wasn't sure if they would support that type of input.

[Blacky]

Yes, the 12V inputs are discrete switches. They switch from off to on at about 3.x volts and from on to off at about 2.x volts. The hysterisis (difference between 2.xV and 3.xV) is to prevent rapid switching at the crossover point.

Regards
Paul

[kbracing96]

Ok, So it won't work, thats what I was wondering. :(

[TAQuickness]

Yes, the 12V inputs are discrete switches. They switch from off to on at about 3.x volts and from on to off at about 2.x volts. The hysterisis (difference between 2.xV and 3.xV) is to prevent rapid switching at the crossover point.

Regards
Paul

Learned something new today :D We call that deadband in my line of work. Hysterisis is what we call deadband in valve action.

[TAQuickness]

Ok, So it won't work, thats what I was wondering. :(

I would think you could scale that down and bring it in via the 5vdc inputs.

[joecar]

Learned something new today :D We call that deadband in my line of work. Hysterisis is what we call deadband in valve action.Control systems. :cheers:

[joecar]

I would think you could scale that down and bring it in via the 5vdc inputs.Kb,

You could scale it linearly by getting two resistors R1, R2 (in the kohm range) in series to ground and tap off from in-between them...

This is a voltage divider, the scaled voltage is:

Vout = Vin * R2 / (R1 + R2)

where R2 is the resistor going to ground, and R1 is connected to Vin.

For example, to scale down by 3 (i.e. to multiply by 1/3):
R1 = 2k4, R2 = 1k2

or some values that give closest ratio (resistors come in specific standard values):
R1 = 6k8, R2 = 3k3

[Blacky]

So who knows if it is spelled hysterisis or hysteresis?
Or are they two separate words with two separate meanings?
Paul

[joecar]

The correct one is hysteresis.

[Blacky]

Doh! I had a 50:50 chance and I got it wrong - again :bash:

[Ira]

I should think the best thing would be to use the PWM to generate a 0-5V analog signal which could then be feed into the analog inputs on the V2.

Ira