signal from an instrument

[zhpipo16]

hello every body i am new in this forum and i want a help please

i want to automate a Keithley 6487 instrument with labVIEW and RS232 and my desire function is to acquit a signal from this instrument and trace him in the graph; so please help me

NB: the Kethley 6487 is an instrument for measurement (low currant and hay resistance) and mu work is to inject a signal sin of tension on the base of a transistor and acquit a signal from the output (collector) ; it is a sin signal so how i can do that please .

thank you

[Francois Normandin]

You can get a driver from NI website:

<http://sine.ni.com/apps/utf8/niid_web_display.model_page?p_model_id=239>

[zhpipo16]

thank you for your interesting

yes i have a driver but the sous VI READ for example or READ DATA cans read one value or currant but i want to read a complete signal do you understand me friend ? any help.......

thank you again.

[Francois Normandin]

QUOTE (zhpipo16 @ Jun 2 2008, 05:27 PM)

thank you for your interesting

yes i have a driver but the sous VI READ for example or READ DATA cans read one value or currant but i want to read a complete signal do you understand me friend ? any help.......

thank you again.

Keithley's website mentions a 1000 readings/s maximum. It is unlikely that you could trigger individual measurements at that rate... You're best option is to use buffered acquisition. Check the manual page section C to get sample programs. You should use the TRACE commands to store

TRIG:DEL 0 (Set trigger delay to zero seconds.)

TRIG:COUN 2000 (Set trigger count to 2000.)

NPLC .01 (Set integration rate to .01 PLC.)

DISP:ENAB OFF (Turn display off.)

TRAC:POIN 2000 (Set buffer size to 2000.)

TRAC:CLE (Clear buffer.)

TRAC:FEED:CONT NEXT (Set storage control to start on next reading.)

STAT:MEAS:ENAB 512 (Enable buffer full measurement event.)

*SRE 1 (Enable SRQ on buffer full measurement event.)

*OPC? (Operation complete query)

INIT (Start taking and storing readings.)

DISP:ENAB ON (Turn display back on.)

TRAC:DATA? (Request data from buffer.)

[zhpipo16]

ok friend and thank you; so after this commands i take a READ or READ DATA VI or make a connection with graph or........

and really thank you very match :thumbup:

[Francois Normandin]

QUOTE (zhpipo16 @ Jun 2 2008, 06:38 PM)

ok friend and thank you; so after this commands i take a READ or READ DATA VI or make a connection with graph or........

and really thank you very match :thumbup:

TRAC:DATA? is the last command. Convert the result (string, probably comma-separated values) and send to graph.

[zhpipo16]

this is my VI , but i don't now how i can make a graph after this commande please help me.

this is my VI , but i don't now how i can make a graph after this commande please help me. i use the VIs of driver of keithley 6487.

[Francois Normandin]

QUOTE (zhpipo16 @ Jun 3 2008, 12:43 PM)

this is my VI , but i don't now how i can make a graph after this commande please help me.

this is my VI , but i don't now how i can make a graph after this commande please help me. i use the VIs of driver of keithley 6487.

First, you should always post your VIs in a library or Zip file when they contain dependencies (Keithley driver in this case).

Second, I suggest you use the VISA palette. What you need is to convert a string to an array of floats. Look at the String palette. There are fine tutorials available in the Help of LabVIEW.

Download File:post-10515-1212524294.vi (LV 8.5)

[zhpipo16]

QUOTE (normandinf @ Jun 3 2008, 09:24 PM)

First, you should always post your VIs in a library or Zip file when they contain dependencies (Keithley driver in this case).

Second, I suggest you use the VISA palette. What you need is to convert a string to an array of floats. Look at the String palette. There are fine tutorials available in the Help of LabVIEW.

Download File:post-10515-1212524294.vi (LV 8.5)

thank you friend normandif i will do this and i will tel you ok?

[Francois Normandin]

QUOTE (zhpipo16 @ Jun 3 2008, 06:26 PM)

thank you friend normandif i will do this and i will tel you ok?

hello again;

i don't understand what you mean about (this part depends on what keithley.......) what i can writ in the pink case .

thank you.

The equipment will answer with a string, which you fetch with the command trac:data?. You have to format this string into useful data (array of numbers) that can be sent to a graph or output to a file at your convenience.

At this point, I strongly suggest you take a look at LabVIEW tutorials. They take a few hours to go through, but you'll gain a lot of experience about the language. The "pink" case is an indicator. I cannot help you if you don't have a basic knowledge of LabVIEW. I don't want to do your homework if you know what I mean... (No offense meant )

[zhpipo16]

hello;

i get a problème again .

well, this is my work (with keithley6487)

1*i have a circuit with a resistance and a diode

2*inject a tension sin with GBF on input(diode) (1)

3*receive a signal from the output (2)

4*but my program show me in the graphe this (3)

5* i receive a signal with the buffer read command (TRAC:DATA?)

6* i make a 200 reading and size of buffer 200

i want to now where is the problem why i had not like signal (2)? help me please

(1), (2) and (3) are in the picture

[zhpipo16]

any answer friends help me please :headbang: .

[zhpipo16]

but why i have not one answer her

please help me

[Clio75]

QUOTE (zhpipo16 @ Jun 7 2008, 09:46 PM)

but why i have not one answer her

please help me

I can answer why you haven't got an answer, but I can tell you how I do instruments at our site

Have you tried to use vise write and visa read, instead of this drivers?

To be honest i have never been able to get them to work like I would like them to do. So I write my own, just by using the protocol and visa boks. Then I have a vi after your own wish.

I hope this helps you

BR

clio

[zhpipo16]

so, i wait a long time for a technical answer, and finaly i get this message?

dear clio75 do you see a the attached file? and are you understand my first message(explaining for my program)?

this is my project for my end of study and this problem is a 10% from my total work, it's the only problem in this work.

And for your question i say: yes, the driver of the keithley6487 has a VI (read) and vi (writ) just like visa read visa write and i take this VIs of driver. So if you have a help , help me else i have not a time please ...

[Clio75]

With so many insults in one reply I not sure I going to help you any more.

If you read my post. You will se I ment use the VISA READ/WRITE and NOT the F..... drivers you have to the F..... instrument.

QUOTE (zhpipo16 @ Jun 8 2008, 07:19 PM)

so, i wait a long time for a technical answer,

This is not a place you can demand an answer. We are ALL LW users helping each other the best we can.

If you need fast tek support call NI or you local dealer.

[zhpipo16]

i am waiting a help please members he doesn't undertand

Clio please if you don't now what is mean a driver of instrument please download any driver from for example www.keithley.com and look his VIs, you will be find the write and the read.

but my problem is not on the writ and the read i now this functions; my problem is with a buffer ok? :headbang:

[Kevin Payne]

QUOTE (zhpipo16 @ Jun 9 2008, 12:30 AM)

i am waiting a help please members he doesn't undertand

I don't have an answer, but I do have a request and a question:-

My request is that you tidy up the block diagram so that you have got all the wires going from left to right and not going backwards. You also need to make sure your wires don't disappear under the sides of the sequence structure. I request this so that we can understand your block diagram.

My question is... do you have a drawing of how you have the instrument connected to the resistor and diode, and what voltage sine wave you are applying? I ask this because the Keithly 6487 is an ammeter for measuring current, yet you seem to be trying to measure voltage with it, so I think I must be not understanding how you have it connected.

[Anders Björk]

QUOTE (zhpipo16 @ Jun 4 2008, 08:54 PM)

hello;

i get a problème again .

well, this is my work (with keithley6487)

1*i have a circuit with a resistance and a diode

2*inject a tension sin with GBF on input(diode) (1)

3*receive a signal from the output (2)

4*but my program show me in the graphe this (3)

5* i receive a signal with the buffer read command (TRAC:DATA?)

6* i make a 200 reading and size of buffer 200

i want to now where is the problem why i had not like signal (2)? help me please

(1), (2) and (3) are in the picture

First you really dont need a flat sequence spanning over the complete diagram. Second you really want a 50 second delay, from the final write to the first read? Third if you would start reading immidately after the last write, what whould get then?

[zhpipo16]

QUOTE (Kevin Payne @ Jun 9 2008, 08:44 AM)

I don't have an answer, but I do have a request and a question:-

My request is that you tidy up the block diagram so that you have got all the wires going from left to right and not going backwards. You also need to make sure your wires don't disappear under the sides of the sequence structure. I request this so that we can understand your block diagram.

My question is... do you have a drawing of how you have the instrument connected to the resistor and diode, and what voltage sine wave you are applying? I ask this because the Keithly 6487 is an ammeter for measuring current, yet you seem to be trying to measure voltage with it, so I think I must be not understanding how you have it connected.

hello;

yes Kevin i want to visualise a current.

1* i will apply e(t)=5sin(100t)

2* the voltage wille be sin v(t)=x*e(t)

3*the current i(t)=v(t)/R

so the currant have a same form of voltage ok?

and i conect a Keithley 6487 with a circuit serialy not parallèle, so i can make this?

and thank you

[Kevin Payne]

QUOTE (zhpipo16 @ Jun 10 2008, 11:18 PM)

hello;

yes Kevin i want to visualise a current.

1* i will apply e(t)=5sin(100t)

2* the voltage wille be sin v(t)=x*e(t)

3*the current i(t)=v(t)/R

so the currant have a same form of voltage ok?

and i conect a Keithley 6487 with a circuit serialy not parallèle, so i can make this?

and thank you

I'll start by repeating my request that you post a tidied version of the block diagram, then I have more questions.

What frequency and amplitude is your input signal, and what sample rate are you measuring at? (I'm hoping you know about the Nyquist frequency). I'm looking for you to reply with numeric values rather than equations.

[AnalogKid2DigitalMan]

Diodes only pass current in one direction (though there is a slight leakage current when they are reverse biased). And they also exhibit a voltage drop when forward biased, the drop depends on the semiconductor materials used in their construction (typically .3 to .7V).

[JiMM]

Another thing that would be usefull is either the data collected or a picture of the ACTUAL data, not a crayon depiction. What is the amplitude and time scale of the data for all three graphs? We cannot guess why it is not working if we also have to guess what it actually is doing. :beer:

[zhpipo16]

but i said e(t)=5sin(100t);

so Amplitide=5v

frequency wt=100 and f=2*3.14*w

but my programme will acquit from any e(t); and it's good (look my attached file in th firste msg) but my probleme is with the buffer when i apply "read"

and my friends this work should be finished this friday, so help me please

[Kevin Payne]

QUOTE (zhpipo16 @ Jun 11 2008, 09:59 PM)

but i said e(t)=5sin(100t);

so Amplitide=5v

frequency wt=100 and f=2*3.14*w

but my programme will acquit from any e(t); and it's good (look my attached file in th firste msg) but my probleme is with the buffer when i apply "read"

and my friends this work should be finished this friday, so help me please

Sorry zhipppo16, but you're not giving us enough information - your original attatchments are missing too much. You need to re-read the replies and get the answers we've asked for, if you want help. Also putting comments on the block diagram explaining the reason for each of the commmands you've sent to the instrument would be a good idea.