Behavior of niSwitch Wait for Scan to Complete with scanning in handshaking mode

[mjohn_v]

Hello,

I was wondering if anyone can tell me, when scanning in handshaking mode, exactly when niSwitch Wait for Scan to Complete.vi returns. I'm assuming it's either when the switch receives the final "measurement complete" signal from the acquisition device or else after the switch returns to its default state, but I suppose it could also be when the switch makes the connection to the final channel in the scan list. If anyone could point me to a place this is documented, I would appreciate it! I see a partial timing diagram in the NI Switch Help file, but it cuts off before the end of the scan.

Thanks!

[this_one_time_at_vancamp]

mjohn_v,

I found a quick mention of it in the NI-SWITCH software user manual: ftp://ftp.ni.com/support/pxi/ni-switch/1.1/321900a.pdf

Page 2-13 mentions it in relation to the Scan operation, which says it returns when Scan is enabled. Following this same logic, maybe its when the state is changed, meaning Wait for Scan to Complete may return when the switch returns to the default state. I will have to do some more looking into this and get back for a more definite answer though.

VanCamp

[marshallg]

>ftp://ftp.ni.com/support/pxi/ni-switch/1.1/321900a.pdf

This document is out of date for modern NI-SWITCH (its from 1998 and refers to an older version of NI-SWITCH).

The niSwitch Wait for Scan to Complete.vi should return when the switch is no longer scanning.  There are three cases where it should return: 1. the finite scan list completes, 2. the scan is aborted, 3. the timeout is reached.  If you are using a continuous scanlist, then the first case (the scanlist completed), will never occur.

Let me know if you see different behavior and I'll investigate further.

 - Marshall

[mjohn_v]

Just to clarify, in this diagram adapted from the section on handshaking from the documentation of the most recent version of NI Switches, you could argue the scan is complete at point A, when the work of the switch is done, or point B, when the work of the DMM is done. I'm wondering if niSwitch Wait for Scan to Complete returns before point B, or at or after point B. Thanks!