continuously check Keithley 6517A to REL instantly after Z-Check completes and first measurement is made

[DBuck42]

I am using a Keithley 6517A to measure charge (Coulombs) via an IEEE 488 connection to LabView. Before a measurement can be taken, however, I need to zero-check (Z-Check, Zch) the instrument and set the relative (REL, Key 30) as soon as the first reading is displayed. If the instrument is still measuring the initial zero-value to which all other values are taken relative to, activating REL will return an error. So I need to send the commands:

: Syst : Zch OFF;

: Syst : Key 30       (without spaces, this dumb setup turns the script into emoticons)

Where the second command (: Syst : Key 30) is not activated until the instrument has measured it's first reading. In other words, I need to continuously query the divce to tell me when the instrument has made it's first reading, then turn on the REL. Any advice on the matter is greatly appreciated! I have attached the Keithley 6517 vi's for reference.

[Bumblebee_Tuna]

Try experimenting with different wait times to send the second command. The user manual for the device might have more information regarding this. 

[DBuck42]

Hi Bumblebee_Tuna,

Thanks for your advice. I have tried a few wait times, but it's fairly inconsistant over many meausrments. I did however manage to trigger a measurement then by simply using the GPIB Read VI with an unlimited timeout followed by the Key 30 within a case structure, the system took the REL instantly after the triggered measurment was read. I hope this helps anone in the future who may encounter the same problem.