USB-1208LS User's Guide Functional Details
USB-1208LS channel gain queue feature
The USB-1208LS's channel gain queue feature allows you to set up a scan sequence with a unique per-channel
gain setting and channel sequence.
The channel gain queue feature removes the restriction of using an ascending channel sequence at a fixed gain.
This feature creates a channel list which is written to local memory on the USB-1208LS. The channel list is
made up of a channel number and range setting. An example of a four-element list is shown in . Table 3-3
Table 3-3. Sample channel gain queue list
Element Channel Range
0 CH0 BIP10V
1 CH0 BIP5V
2 CH7 BIP10V
3 CH2 BIP1V
When a scan begins with the gain queue enabled, the USB-1208LS reads the first element, sets the appropriate
channel number and range, and then acquires a sample. The properties of the next element are then retrieved,
and another sample is acquired. This sequence continues until all elements in the gain queue have been selected.
When the end of the channel list is detected, the sequence returns to the first element in the list.
This sequence repeats until the specified number of samples is gathered. You must carefully match the gain to
the expected voltage range on the associated channel—otherwise, an over range condition can occur. Although
this condition does not damage the USB-1208LS, it does produce a useless full-scale reading. It can also
introduce a long recovery time from saturation, which can affect the next measurement in the queue.
3-12
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