Omega manual OM-USB-1208FS channel gain queue feature, Error band plot

OM-USB-1208FS User's Guide Functional Details

The accuracy plots in Figure 12 are drawn for clarity and are not drawn to scale.

Figure 12. Error band plot

OM-USB-1208FS channel gain queue feature

The OM-USB-1208FS'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 OM-USB-1208FS. The channel list is made up of a channel number and range setting. An example of a four-element list is shown in the table below.

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 OM-USB-1208FS 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 OM-USB-1208FS, 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.

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