USB-1208FS: Load the channel/gain queue. The USB-1208FS can scan an
arbitrary sequence of analog input channels, each with an arbitrary gain
setting. DaqALoadQueue allows you to specify that sequence.
DeviceIndex” is a small integer, the array index specifying which HID
device in the array returned by PsychHID(‘Devices’) is interface 0
of the desired USB-1208FS box.
“channel” is a vector of length 1 to 8; each value (0 to 15) selects any of
various single-ended or differential measurements.
“channel” Measurement
0 0-1 (differential)
1 2-3 (differential)
2 4-5 (differential)
3 6-7 (differential)
4 1-0 (differential)
5 3-2 (differential)
6 5-4 (differential)
7 7-6 (differential)
8 0 (single-ended)
9 1 (single-ended)
10 2 (single-ended)
11 3 (single-ended)
12 4 (single-ended)
13 5 (single-ended)
14 6 (single-ended)
15 7 (single-ended)
“range” is a vector of the same length, with values of 0 to 7, specifying
the desired gain (and voltage range) for the corresponding channel…
unless we’re talking channels greater than 7. Single-ended inputs always
have a range of +/- 10 V, so if you try to set the range to anything other
than zero for a single-ended measurement, your setting will be ignored.
For differential measurements (channels 0:7), the mapping between the
values passed to this function and the gain (and actual range) are:
0 for 1x (+/-20 V), 1 for 2x (+/-10 V),
2 for 4x (+/-5 V), 3 for 5x (+/-4 V),
4 for 8x (+/-2.5 V), 5 for 10x (+/-2 V),
6 for 16x (+/-1.25 V), 7 for 20x (+/-1 V).

DeviceIndex” has the same meaning here as for the USB-1208FS.
“channel” is a bit different…
Only single ended inputs are defined for the 1608FS, so channels range
only from 0 through 7. Also, when the gain queue is loaded, it is
supposed to be loaded for all 8 channels – AInScan does not allow you to
use the gain queue as a way to determine which channels to check; you can
*NOT* scan an arbitrary sequence of channels in a 1608 box like you can
with a 1208 (and I believe 1408) box. There also appears to be no way to
poll any of the device to find out the current state of the gain queue.
All of this means choices have to be made. To keep this function as
similar as possible for operations of both types of device, user is still
allowed to pass an arbitrary set of channel/gain pairs (as long as there
no repeats), and the function will do its best not to touch the gains of
other channels. To be safe, you should always specify the gains for all
8 channels, but I figure you will only read from the channels whose gains
you explicitly set… Even though that behavior does not happen
automatically through calls to this function as it may with the 1208FS.
However, since we cannot poll the device to find out the current gain
queue settings, we’re going to try to use a Preferences file. I suspect
this will generally work, but if multiple accounts use the device or if
the device is sometimes attached to a different machine, then this
function may cause some gains to get changed even if not specified by the
user. Did I mention that you should always specify the gains for all 8
channels? Anyhoo…
“range” has the same conceptual meaning for the 1608 as it does for the
1208, but the numbers are different:

0 for 1x (+/- 10 V),      1 for 2x (+/- 5 V),  
2 for 4x (+/- 2.5 V),     3 for 5x (+/- 2 V),  
4 for 8x (+/- 1.25 V),    5 for 10x (+/- 1 V),  
6 for 16x (+/- 0.625 V),  7 for 32x (+/- 0.3125 V).  

See also Daq, DaqFunctions, DaqPins, DaqTest, PsychHidTest, DaqAIn,
DaqAInScan, DaqAInScanBegin.

4/15/05 dgp Wrote it.
1/8/08 mpr created behavior appropriate for 1608
6/23/15 mk Make compatible with Octave, fix 1608-FS pref file caching.

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