Thank you for responding so quickly Dennis.
BACKGROUND:
I am a software developer and in the past have coded applications for PLC. I am new to DAQ equipment from NI. By the way I have found NI to the most incredible company I have ever come across, very well organized, mature organization, super support and innovative products
I am using a DSA 4552, 6040 and a 6013.
This is an application which runs a prototype engine.
The original problem I have is that the magnetic crank trigger sensor, which is used to trigger the spark in an ignition module is too noisy to be used by the DAQ cards. When the magnetic sensor is not connected to the ignition module it produces a nice clean analog signal but when connected to the ignition module the signal is totally obscured by noise from the ignition module. The ignition module is a MSD 6 plus which produces 40,000 volt multiple sparks for 20% of a rotation. I can not isolate the spark noise from the Tachometer output on the ignition module, nor from the crank trigger sensor itself. My solution is to use a second hall sensor which is isolated from the crank trigger sensor and use that signal to drive the engine control system which uses the DAQ card mentioned above. The timing offset between the two sensors will be corrected in software.
For design reasons (physical space limitations) it is best to use two of the new hall sensors as they are much smaller and produces a cleaner digital signal.
Problem is that the new hall sensor produces a sinking output.
This works OK for the DAQ application but not for the ignition module as it requires a rising signal.
I have spoken to the supplier and they gave me a schematic to create a pull-up resistor to convert the sinking pulses (5+ 0) into rising pulses (0 5+). Problem is that it did not work. Perhaps the transistor I used was bad. I have heard that there are other ways to achieve the same result, but have not found one yet. Do you know of one? I would prefer to simply purchase a device that will do what I need.
What I made last night using the diagram I was given. It uses a 2N4401 transistor and a 4.7 K resistor.
The sinking signal form the Hall sensor is connected to “E”, ground is connected to “B”, and a 4.7 K resistor to the “C” lead of the transistor. Then 5+ volts is connected to the other side of the resistor. The rising output is supposed to be obtained from making a connection between the resistor and the C lead of the transistor. All I get is a steady 5+ volts with no signal whatsoever.
THE APPLICATION and another solution:
I use a hardware analog trigger to sense the sinking output and then use ATC_OUT to gate counter_0. Counter_0 measures the period of the pulses and I use this value together with other parameters to modulate a fuel injector. The RPM measured with counter_0 is used modify the width and delay of two other counters which create a re-triggerable finite pulse train. This re- triggerable finite pulse train is what is used to modulate the fuel injector. This all works fine until the ignition module is connected to the crank trigger and the noise problem causes the system to not work.
Another way to get the rising signal to the ignition module might be to route the ATC_OUT to a PFI pin and then use a pull-up resistor to convert the 5 volts signal to a 12 volts signal. I believe this form of pull-up resistor is also called a voltage level shifter. In shis way I would only have to use one hall sensor. Do you know if this would work? Do you know how to make a voltage level shifter?
Thanks
**Sorry for the long note.
Cheers
Bruce
