NI-scope disconnect routing BUG??

[Henrik_Volkers]

I use a 5922 synced with a 6652 and a 5124.

running the task I want to tried to route the start trigger to the PFI0 or PFI1 , however routing NONE to PFI0 or PFI1 doesn't seems to disconnect the routing.

I attached a simple vi for test. One additional cable to monitor the PFIs mini DIN output to a scope is needed 🙂

1. choose the 5922, run the vi,
2. hit read (some samples are taken)
3. activate PFI0 button (START TRIGGER is routed to PFI0)
4. hit read (see the trigger pulse on the PFI0)
5. deactivate PFI0 button (NONE is routed to PFI0)
6. hit read ( uups, trigger pulse still there)

Is this a BUG or how do I disconnect the start trigger signal from the PFIs without loosing my sync?

[Nathan-P · Accepted solution]

Henrik,

I see the problem, your code does work the way you described, but how you are attempting to unset the FPI lines in incorrect.  In the documentation for niScope Export Signal it states "To unprogram a specific line on a device, call this VI with the signal you no longer want to export and set output terminal to None."

In your code, you are writing  you are writing Start Trigger to PFI0, which enables PFI0 export of the Start Trigger.  To undo this, you need to write Start Trigger to None (not PFI0).  You are writing "none" to the wrong input of the vi.

Attached is a copy of your VI that correctly unset's the PFI routing.

I hope this helps!

Nathan

[Henrik_Volkers]

Thank you 🙂

RTFM helps 😉

[Henrik_Volkers]

Quick question

is there a way to tie the PFI outputs of a 5922 to GND?

I can route the signals wanted and disconnect them now 🙂   but after routing to none  (even with a 10k pull down) I have some voltage* left.

Doesn't seem to tristate ....

*) 15mV ... no real problem ... but seems that there is are some internal resistors at the ouput of a PFI....  any information on this?

[Nathan-P]

Correct, there is no option in the driver to connect the PFI lines to ground.  Internally there is a 150K pull up resistor connected to the PFI line outputs.

Nathan