Serial Commands Keithley 2700

[myannell]

Looks like my full original message didn't display properly... so here it is:

I am completely new to LabVIEW. I'm trying to interface with a Keithley 2700 through an RS232 serial connection and am currently lost. I found a few helpful hints online that got me to where I am now, but currently my VI won't take measurements.

I downloaded the Keithley 27XX drivers and they all work on the system I am running, giving me accurate readings. I believe the main issue with my VI is the 'write buffer' string connecting to my VISA Write. I don't know how commands are ordered or phrased for the VISA Write and I can't seem to figure it out just from the manual.

As of right now I am just trying to take a resistance measurement (2 wire) and have it display on my Front Panel.

Anything helps,

myannell

p.s. when I leave the 'write buffer' string blank the VI runs without error

[Dennis_Knutson]

Use Help> Find Instrument Drivers and search for 2700. No need to reinvent the wheel.

[myannell]

Original post edited, my second comment is now irrelevant.

[Omar_II]

I think you need to add a Termination Character to your write string.

From the Keithley manual

Terminator
The Model 2700 can be configured to terminate each program message that it transmits to
the controller with any of the following combinations of <CR> and <LF>.
<CR> Carriage return
<CR+LF> Carriage return and line feed
<LF> Line feed
<LF+CR> Line feed and carriage return

With the correct Termination and Time out get rid of the delay and bytes at port calls

Try a simple *IDN? Command and see if you still get an error.

[myannell]

I compiled a VI that from the picture above but it just returns read buffer "!!KEITHLEY" and error out code -1073807339. Any ideas?

[Dennis_Knutson]

Look at the initialize function in the driver you downloaded. Please take a few tutorials on basic instrument communication and learn what termination characters are.

[Omar_II]

---

@myannell wrote:

I compiled a VI that from the picture above but it just returns read buffer "!!KEITHLEY" and error out code -1073807339. Any ideas?

---

From the Keithley Manual you should get something like this back

KEITHLEY INSTRUMENTS INC., Model 2700, xxxxxxx, yyyyy/zzz

*IDN? — identification query Reads identification code

The identification code includes the manufacturer, model number, serial number, and firmware
revision levels and is sent in the following format:
KEITHLEY INSTRUMENTS INC., Model 2700, xxxxxxx, yyyyy/zzz
Where: xxxxxxx is the serial number.
yyyyy/zzzzz is the firmware revision levels of the digital board ROM and
display board ROM.

I don't have a 2700 available but the code worked on a Keithley 2015 that I do have.

I can't say that I have every seen the reply "!!KEITHLEY"

This make me think that the 2700 is not setup correctly

The error is a time out error. The Terminator was not received back from the Keithley.

Can you try a terminal program (TeraTerm, YAT, etc)?

You say the  Keithley 27XX drivers works. When you run just the 27XX Initialize.vi with the ID Query set to True/Yes do you get the same error. Open the block diagram of 27XX Initialize.vi and you will see that what I sent you is about the same as how the driver does it. No Wait or Bytes at port between the Write and Read.

Make sure the Terminator setting on the 2700 matches the software settings.

[Tushar16]

I am also trying the same examples using serial comm in LV 15. I am using ''Keithley 27XX Finite Multi Read/ Single Measurement'' for front and rear panel measurement. As far as the front panel is concerned I can measure all the parameters, But while using the rear panel with 7702 module I can only measure DC Voltages and nothing else (ACV, DCi,DCV,Resistance etc). Every time I try to measure some thing other than DC voltage I get an error message, error-221(Settings conflict). I am attaching the file too. Any kind of help is appreciated.

[Machop]

It seems that the settings error is related with a worng configuration on the device. Does the Keithley  supports that kind of measurements? 

[Tushar16]

Well Keithley does support those measurements but the keithley 2700 DMM that i was using had A02 firmware installed in it. Switched it with B03 and that baby gave some pretty nice results. Though the problem now is that i have a 7702 multiplexer card and i wish to measure current across 25-30 probes but 7702 only offers 2 dedicated channels for current measurement, which is quite shitty.