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Warm Up Period

DMM7510 7½-Digit Graphical Sampling Multimeter
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Wade_Patrick
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Warm Up Period

Post by Wade_Patrick » September 2nd, 2016, 1:38 pm

I have tried what was suggested in the documentation, about looking at the internaltemp, to see if the 90 minute warm up period is complete. But, I'm missing something. Does someone know what TSP code, would tell you how long the meter has been powered up, or if it is done with warmup?

brian.d.smith
Keithley Applications
Keithley Applications
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Re: Warm Up Period

Post by brian.d.smith » September 3rd, 2016, 12:54 am

Please have a look at the DMM7510 Reference Manual page 3-44

3. Turn on instrument power and allow the instrument to warm up for at least 90 minutes. When the
instrument has completed the warm-up period, a message is displayed and an information event
is generated in the event log.

You can peruse the event log from the front panel.
You can save the event log to a file on the USB flash drive.
You can read the event log with a SCPI command
You can read the event log with a TSP command

If you search the Reference Manual for "event log" you will see all of the above described in detail.

Wade_Patrick
Posts: 8
Joined: December 8th, 2015, 1:03 pm
Country: United States

Re: Warm Up Period

Post by Wade_Patrick » September 6th, 2016, 12:36 pm

Yes I read all of that, and wondered if that's really the only way to read a status?

So what do I read when someone presses the "Clear Log" button on the "Log Settings" screen? Is there a way to read the "Warmup Ready" status on the calibration screen. Or, call the *CLS command, or the status.clear() command, or :STATus:CLEar command. Or, let the event log overflow.

AND, there's this small problem:
"When an event occurs on the instrument, it is placed in the event log. The
:SYSTem:EVENtlog:NEXT? command retrieves an unread event from the event log. Once an event
is read, it can no longer be accessed remotely. However, it can be viewed on the front panel."

So, I run a test, I check and warm up is done. I run another test, it checks and warm up is not in the event log, because I read it in the previous test. What do I do about this?

brian.d.smith
Keithley Applications
Keithley Applications
Posts: 402
Joined: June 10th, 2013, 6:00 am
Country: United States

Re: Warm Up Period

Post by brian.d.smith » September 12th, 2016, 7:54 am

I am confused why you want to read the status of warm up more than once? When the instrument achieves warm up status, it is warmed up for all time until you turn off the instrument.

The behavior of the event log when read remotely is that of a software stack. When you pop a stack, the item that you popped is no longer on the stack. You have to push an item back onto a stack for it to not be lost. There is not mechanism to to push an event back into the event log.

If your remote control program reads the event log, you can simply save that event in a global variable if you need to read the event again.

Please feel free to illuminate further your need to read an event more than once.

Wade_Patrick
Posts: 8
Joined: December 8th, 2015, 1:03 pm
Country: United States

Re: Warm Up Period

Post by Wade_Patrick » September 14th, 2016, 8:05 am

The DMM7510 is being controlled by an embedded processing system, that is self-calibrating its own power supplies. So, when you power down the computer controlling the DMM, and remove it along with the board, and then put in a new CPU and board to calibrate and test, and power it back up, all global variables are gone.

Even on a traditional calibration system with a standard desktop host computer, how do you know someone didn't power cycle the meter behind your back? Are you required to open a socket to the meter, and keep it open forever? Do you wait 90 minutes if a Ethernet comm locks up, and you have to restart the socket? I don't understand how you maintain tractability to your published accuracy specs with your meter, if the state of the meter can't be verified at any time.

"Warmed Up" is a STATE, not an EVENT. I need to read the STATE of the meter, just like you display it on the screen as a STATE. You don't display it as an event, that goes away after some time or event.

brian.d.smith
Keithley Applications
Keithley Applications
Posts: 402
Joined: June 10th, 2013, 6:00 am
Country: United States

Re: Warm Up Period

Post by brian.d.smith » September 16th, 2016, 9:05 am

What you seek to know may be covered on page 230 of the reference manual

*************************************************************************************************

Monitoring internal temperature

You can monitor the temperature difference between the actual internal temperature and the
temperature when auto calibration ran through the panel or by using remote commands. With remote
commands, you can also check the present internal temperature and the internal temperature when
auto calibration was last run. Temperature is returned in Celsius (°C).

The internal temperature is not updated on the Calibration screen until the warmup period is
complete. The remote commands always return the present temperature.

From the front panel:
1. Press the MENU key.
2. Under System, select Calibration.
3. The Temperature Difference is displayed.

Using SCPI commands:

For the present internal temperature, send:
:SYSTem:TEMPerature:INTernal?

For the temperature difference, send:
:ACAL:LASTrun:TEMPerature:DIFFerence?

For the temperature when auto calibration was last run, send:
:ACAL:LASTrun:TEMPerature:INTernal?

Using TSP commands:

For the present internal temperature, send:
print(localnode.internaltemp)

For the temperature difference, send:
print(acal.lastrun.tempdiff)

For the temperature when auto calibration was last run, send:
print(acal.lastrun.internaltemp)

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