Keithley 2750 triggering problem; Labview

[Grugh_Mike]

I am using a 2750 Keithley DMM along with three 7702 scanner cards.

I want to use the a single computer, a single GPIB card and a single Keithley 2750 to perform two processes.

I am thinking of employing 3, 7702 scanner cards; so that i will get 60 lines to scan.

Two processes need to be measured using this arrangement.

1st one: The resistance value of 30 sensors are to be measured using scanner 1(20) and scanner 2(10).

     This is performed once in every cycle. (ie. based on a trigger signal that is generated on reaching a particular                position )

2nd one: Every 1 hour the rest lines should be scanned (ie. scanner 2 (10) scanner 3 (20) )

The problem i have is, if the Keithley is triggered by both the processes at the same time, wont it return an error?

How to solve this?

Thanks in advance.

[Henrik_Volkers]

You didn't tell how critical the timing is 😉

So I assume the 1h task is less critical and software timing is possible.

I would use a producer consumer architecture.

And put each channel of the 1h task as a seperate reading entrance into the queue.

If during the 1h task the position trigger for the first task arrives, you can enqueue that channellist prior to the rest of the 1h task list.

Maybe the tricky part is to capture the triggerinput of the 2750 in software without starting a measure task. I don't know the keithley...

Another solution is to read all channels every hour and and at the trigger signal. Digg into the manual or ask a keithley app-ing how the trigger will behave. 

[Grugh_Mike]

Thanks for the reply Henrick.

I have another way to figure things out.

But i would like to know whether there is any command to check whether Keithley 2750 is busy or not.

My 1st task is of more priority than the second one.

So that will have to be triggered anyway depending on signal from the sensor.

The 2nd task can be carried out only if Keithley is free, else shift the measurement time 2 minutes later.

So is there any command to check whether Keithley is free?

Please confirm whether my solution will function.

Thanks in Advance.

[Henrik_Volkers]

Time to RTFM (Read the f****** manual) 😉

Usually these type of instuments have a status register aka a byte where a certain bit is set if busy.

Some also have a dedicated request command to find out if a scanning task is running.

[Grugh_Mike]

RTFM...nice abbreviation.

like it.

Let me do that first.