I have a bit of a dilemma; I have a bi directional meter, the flow output uses a quadrature Frequency (+-90 out of phase). The device that receives the signal cannot accept this signal, but two separate frequencies. Is there a device that can convert the quadrature frequency in to to separate frequencies (one for each direction)?
Eng-Tips is the largest engineering community on the Internet
Intelligent Work Forums for Engineering Professionals
-
Congratulations waross on being selected by the Tek-Tips community for having the most helpful posts in the forums last week. Way to Go!
Quadraature Frequency
- Thread starter SaskGear
- Start date
- Thread starter
- #3
Yes it is a 2 wave frequency proportional to flow rate, in the forward direction they are +90° out of phase and in the reverse direction they are -90° out of phase. The output type is an open collector. I don’t voltage level off hand. There is no PLC on site just the meter and a blow computer that cannot handle this type of signal. Is there a simple device that can seperate the frequency to two seperate.
SaskGear,
I tried a web search for Quadrature Decoder, it seems this terminology has been hijacked.
Anyway an incremental encoder vendor might have a solution.
The following link describes salvaging parts from a computer mouse, there must be a quadrature detector chip in there. On that thought does your blow computer have a mouse input, perhaps you could wire your speed detector in there somehow.
I will be interested to see how you finally resolve this problem.
BTW what's a blow computer?
Regards
Roy
I tried a web search for Quadrature Decoder, it seems this terminology has been hijacked.
Anyway an incremental encoder vendor might have a solution.
The following link describes salvaging parts from a computer mouse, there must be a quadrature detector chip in there. On that thought does your blow computer have a mouse input, perhaps you could wire your speed detector in there somehow.
I will be interested to see how you finally resolve this problem.
BTW what's a blow computer?
Regards
Roy
- Thread starter
- #7
LOL
A Blow computer is just a typo for a FLOW computer used to calculate the flow volume and adjust for Pressure and Temp
I got some clarification on the Frequencies
It is actualy 2 frequencies one gives the open collector signal and the seconed is the same frequency only out of phase depending on the direction of the flow.
What the "FLOW" computer needs is a seperate frequency for each diredtion.
A Blow computer is just a typo for a FLOW computer used to calculate the flow volume and adjust for Pressure and Temp
I got some clarification on the Frequencies
It is actualy 2 frequencies one gives the open collector signal and the seconed is the same frequency only out of phase depending on the direction of the flow.
What the "FLOW" computer needs is a seperate frequency for each diredtion.
Itsmoked.
OK, I owe you one! Silly me! LOL
SaskGear,
Yes, I understand what the quadrature signal is for so as I understand you only need to separate the 2, frequencies is that right?
As I said the encoder vendors might have something or you could make your own using the components from an old mouse (older the better I think) I'm almost certain that the mouse output is one or the other depending on direction of travel, should be easy to check.
Please post the model No of the transducer/and computer. I assume they are from different vendors otherwise the computer would already take care of it.
Roy
OK, I owe you one! Silly me! LOL
SaskGear,
Yes, I understand what the quadrature signal is for so as I understand you only need to separate the 2, frequencies is that right?
As I said the encoder vendors might have something or you could make your own using the components from an old mouse (older the better I think) I'm almost certain that the mouse output is one or the other depending on direction of travel, should be easy to check.
Please post the model No of the transducer/and computer. I assume they are from different vendors otherwise the computer would already take care of it.
Roy
From what has been said, it appears to me that the FLOW computer wants two pulse streams, one for positive flow and one for negative flow.
So if you have quadrature signals A and B, use a D type Flip Flop with A to the D input and B to the clock. The FF will be set or reset depending on the direction of the A/B signals. Then use the FF outputs to gate (ssy) the A signal using two AND gates.
Two double the frequency, Exclusive OR the A and B signals.
So if you have quadrature signals A and B, use a D type Flip Flop with A to the D input and B to the clock. The FF will be set or reset depending on the direction of the A/B signals. Then use the FF outputs to gate (ssy) the A signal using two AND gates.
Two double the frequency, Exclusive OR the A and B signals.
Roy; Not enough description for it to sink in for me on a quick read. Especially while marveling at such a absurdly lamoid computer setup that needs a different pulse train for each direction!
Keith Cress
kcress -
Keith Cress
kcress -
Itsmoked, I agree, it must be a turbine flowmeter eh? to have quadrature output. I thought the link I posted was quite interesting.
The computer mouse must be similar. I will try to find an old one with DIL components that I can see. I tell my wife that it's OK she is loosing her good looks, my eyesight is failing to match.
Roy
The computer mouse must be similar. I will try to find an old one with DIL components that I can see. I tell my wife that it's OK she is loosing her good looks, my eyesight is failing to match.
Roy
- Status
