SCOPE Soft Front Panel

[nyborn]

Hi DFGRAY:

I disconnected the cables from my current source to AI+ and AI- inputs to the CB-68LP. I left it open. Then I put a positive lead to R1 of the device under test and negative lead to the R1 of 5112. I started measure the voltage across R1. The voltage I measured in R1 (100ohm) was correct. Then I increased the value of R1 to 100Kohm. Finally, the 100kohm measuring currect was not correct becasue of the fact the the higher the resistance, it will limit the current compared to the actual value I measured in AI+ and AI- without digital line connected to CB-68LP, Am I doing correctly or right? See attached picture 1.

If it is right, the second question is how you are sure that the current flowing through the current source which is the old setup of the R1 is the actual current flowing the BNC cable under device under test. Is it because you know there will no current go to HAMLIN REED RELAY due to a open switch of the block diagram that I gave you and the current source is left open without a resistor in the block digram, so you are sure you can measure the current under the BNC cable for sure, am I correct?  See attached picture 2

Yes, I am controlling the system with the 6250 and the digital signals on the 6250 were configured as outputs. The hardware way I set up for 6250 with digital I/O is my attached digram. Would you pls help me to make sure the hardware setting are correct.See picture 4

 I put a ground cable from the test tixture to the R1 the end of the NI5112. As you know I use 4 push buttons to generate the output. CH1 push button is reset button, CH2 is enable button, CH3 is bark signal button, CH4 and CH5 are both in the same button called shock test buttons. The way you operate in test fixture is different than using in test panel. In test fixture, you press the eable button, the light is on and you press the bark button, the light is on. Then you press the shock test button, the light is on and the go off. If you operate in the test panel, the output line 1 which I set for enable button is uncheck all the time and the output line 2 which I set for bark button is uncheck all the time, otherwise when I uncheck line 4 for shock test button, the light of enable button and bark button will go off. I guess it is because of the logic of the design in CH2-4 (shock test light button) and in CH2-5 (shoch test button) using in test panel opeartion for digital I/O rather than push buttons. See picture 5

.

Also, am I suppose to follow what the light behave using the push buttons to judge that the opeation of using the check box to opeate in test panel correctly? As you know, the block digram of my design is using push buttons rather than digital I/O button. According to this changes and follow the logic in the block digram, the CH2-4 and CH2-5 is controoled by two check box on the test panel and it was controlled by only one push buttons. Due to this changes, it might also affect the light opeation and the no 4 (CH2-5) opeation in the test panel, am I correct? i suppose to follow what I see in the operation of light in my fixture and then judge that the opeation of using the checkbox of digital are correct? am I right? See picture 6

In this hardware setup, I can either use Diff or RSE mode for measuring current. They both measuring on the same wire (AIGND) in RSE mode of 5112. I don't understand why I have to use diff mode for AI+ and AI- in CB-68LP when the BNC cable is connected to 5112. Is it because in order to measure the current of my test fixture  from the currect source to CB-68LP with the BNC cable connected 5112, since those output are on different ground wire, the way to measure the current from the current source is using the diff mode beause the ground on diff mode would be different than the ground on 5112. They are seperated, I don't understand why it can measure. See attached pic 3

[nyborn]

Hi DFGRAY:

Somehow it posted in page 4, so I would like to post here on page 5. I think it will be much easy to see the problem for verifying here.

I disconnected the cables from my current source to AI+ and AI- inputs to the CB-68LP. I left it open. Then I put a positive lead to R1 of the device under test and negative lead to the R1 of 5112. I started measure the voltage across R1. The voltage I measured in R1 (100ohm) was correct. Then I increased the value of R1 to 100Kohm. Finally, the 100kohm measuring currect was not correct becasue of the fact the the higher the resistance, it will limit the current compared to the actual value I measured in AI+ and AI- without digital line connected to CB-68LP, Am I doing correctly or right? See attached picture 1.

If it is right, the second question is how you are sure that the current flowing through the current source which is the old setup of the R1 is the actual current flowing the BNC cable under device under test. Is it because you know there will no current go to HAMLIN REED RELAY due to a open switch of the block diagram that I gave you and the current source is left open without a resistor in the block digram, so you are sure you can measure the current under the BNC cable for sure, am I correct?  See attached picture 2

Yes, I am controlling the system with the 6250 and the digital signals on the 6250 were configured as outputs. The hardware way I set up for 6250 with digital I/O is my attached digram. Would you pls help me to make sure the hardware setting are correct.See picture 4

 I put a ground cable from the test tixture to the R1 the end of the NI5112. As you know I use 4 push buttons to generate the output. CH1 push button is reset button, CH2 is enable button, CH3 is bark signal button, CH4 and CH5 are both in the same button called shock test buttons. The way you operate in test fixture is different than using in test panel. In test fixture, you press the eable button, the light is on and you press the bark button, the light is on. Then you press the shock test button, the light is on and the go off. If you operate in the test panel, the output line 1 which I set for enable button is uncheck all the time and the output line 2 which I set for bark button is uncheck all the time, otherwise when I uncheck line 4 for shock test button, the light of enable button and bark button will go off. I guess it is because of the logic of the design in CH2-4 (shock test light button) and in CH2-5 (shoch test button) using in test panel opeartion for digital I/O rather than push buttons. See picture 5

.

Also, am I suppose to follow what the light behave using the push buttons to judge that the opeation of using the check box to opeate in test panel correctly? As you know, the block digram of my design is using push buttons rather than digital I/O button. According to this changes and follow the logic in the block digram, the CH2-4 and CH2-5 is controoled by two check box on the test panel and it was controlled by only one push buttons. Due to this changes, it might also affect the light opeation and the no 4 (CH2-5) opeation in the test panel, am I correct? i suppose to follow what I see in the operation of light in my fixture and then judge that the opeation of using the checkbox of digital are correct? am I right? See picture 6

In this hardware setup, I can either use Diff or RSE mode for measuring current. They both measuring on the same wire (AIGND) in RSE mode of 5112. I don't understand why I have to use diff mode for AI+ and AI- in CB-68LP when the BNC cable is connected to 5112. Is it because in order to measure the current of my test fixture  from the currect source to CB-68LP with the BNC cable connected 5112, since those output are on different ground wire, the way to measure the current from the current source is using the diff mode beause the ground on diff mode would be different than the ground on 5112. They are seperated, I don't understand why it can measure. See attached pic 3

DFGR

[nyborn]

Dear DFGRAY:

The passage might be too long, but I have already draw the picture casue without drawing the picture. It is very hard to know if I got the setup correctly for sure. I hope you can forgive this long passage. I will handle the small problem later on. So, pls don't worry. .

[DFGray]

Your 6250 and 5112 connections are fine.  You are correct about why the current can be measured at the 5112.

There are two major problems I can see with your digital circuit.  The first is that, to control the system from the 6250, lines 4 and 5 must always be opposite each other.  This is guaranteed by your hardware pushbuttons, but you will have to connect it correctly and/or program it correctly if you want to automate it through the 6250.  The second is that the digital ground connection should not be at the 5112 input.  You would be better off putting it at the ground on the 7805 power supply or some other such direct connection to the digital power system.  Unless you have added one, there is no connection between the digital power ground and the 5112 ground.  This will cause ground loop problems, which will get worse if you use a large resistor for R1.

If you have the 5112 connected, you must measure current-to-ground through the resistor R1 as you presently have it.  You cannot do it in the old position.  In the current position, you can use either differential or RSE mode, for reasons we have discussed before.  In the old position, with the 5112 disconnnected, you could also use either differential or RSE, for the same reasons.  With the 5112 connected and the resistor in the old position, the current through the resistor will not be correct, no matter what mode you use the 6250, since some (all) of the current will be going to the 5112 ground, making your measurement inaccurate.

[nyborn]

Hi DFGRAY:

In your previous mail, you said I have two major problem in my digital circuit. The first problem is that, to control the system from the 6250, line 4 and 5 must always be opposite each other. This is guraanteed by my hardware pushbuttons, but I will have to connect it correctly if I want to automate it through the 6250. So, I made a digram and I connected the DGND on CB-68LP to GND ground of the test fixture. Am I connect it correctly? I would like you to verify.

If this is correct, I have attached the configuration of the check box in test panel to control the system. According to what you said, line 4 and line 5 must alway be opposite each other. If you see the picture 4 that I attached, the sequence of the opeation of push buttons are as follows. 1) press the reset push button, the light go on and then off. 2) press the enable button, the light go on all the time even though the button release. 3) press the bark button, the light go on all the time even though the button release, 4) the test buttons lights on when press and turn off when release to generate the shock and beep signals after releasing.

If you see the picture 3 of my config, line 4 is on and line 5 is off, the shock and beep signal will generate. I don't quite understand here because the hardware is generated the shock and beep signal after releaing the shock test buttons. As you know the shock test buttons oppsite each other. But in test panel, how am I see this as a shock test buttons in the hardware? I am doubt here. Could you explain to this appearance if the hardware connection of DGND and GND of the test fixture is correct?

[DFGray]

If any of your digital lines are working, and your analog is still working, then your digital ground is probably in an acceptable place.  Without looking at your actual setup, I can not verify this.

Please take the time to understand your digital logic.  Until you know what is going on, you will be thrashing.  If you really want to run your experiment with the 6250, you can remove most of the digital logic from your circuit (the 74HC00s and the 74LS123) and replace it with programmed instructions from the 6250.  I will not tell you how to do this, since you are far better off if you understand what is going on and can reproduce it in LabVIEW/LabWindows/CVI/C/C++ with the 6250.  It is fairly simple, but will require programming.

If you do not wish to remove the logic from the experiment, you will still need to write a simple program to reliably generate the signals for digital lines four and five (one high, one low, followed by both high, followed by a reverse in the original states).  The test panels will not do this well.

Take the time to learn your tools.  If you don't know how to do something, look at the documentation.  Most NI Software has a getting started guide which serves as an excellent tutorial (I learned the basics of LabVIEW over a 3 day period while doing a project similar to yours using the getting started guide for LV3.0).  You can also take advantage of NI customer education, if it is available in your area.

Take home message - learn your setup.  Learn how it works and why it works.  Then you can modify it easily and with confidence.

[nyborn]

Hi DFGRAY:

I tried to follow your guildlines. I found two problems and I am very confuse.

Attached is my pictures of the hardware setup, would you pls help me to verify?

1) The first problem is the digital ground. As you know my block digram of the test fixture, I have a hard ground from the 0-scope, the digital ground will not be affect by the hard ground, right? even though the hard ground is pulling the digital ground of the 6250, the +5V (TTL signal) is still not be affected right? because I just want to have either 5V or 0V to input the logic gate from the push buttons. I am sure if I connect like this, will there be causing a ground loop or there is a little bit potential difference, I don't need care. Could you pls verify me if I am thinking it right?

2) The second question is the other attaced files (digitalIO.vi and word file) as you can see, The line 4 is low and the line 5 need to press low and then press high in order to generate beep and shock signal on a signal shock test button. That is not the way as Line 4 go high and the line 5 go low this principal to generate the shock signal and beep sound. Why? Also, how can I make Line 4 and line 5 (two channels) in one push button?

[nyborn]

The picture size is large, so that is why it needed to cut. sorry for any inconvience. The file is organized by order