Measurement-computing miniLAB-1008 Manual do Utilizador descarregar pdf (Página 24)

miniLAB 1008 User's Guide Functional Details

Combining these two error sources in , we have a plot of the error band of the miniLAB 1008 for the

±10 V range. This is a graphical version of the typical accuracy specification of the product.

Figure 3-12

Figure 3-12. Error band plot

The accuracy plots in Figure 3-12 are drawn for clarity and are not drawn to scale

-FS

+FS

Input Voltage

4095

9.77mV

2048

Output Code

Ideal

Ideal +9.77mV + 20 mVIdeal +9.77mV + 20 mV

Ideal -(9.77mV + 20 mV)

Ideal

Ideal +9.77mV + 20 mV

Channel gain queue

The miniLAB 1008'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 miniLAB 1008. This list is made up

of a channel number and range setting. An example of a four-element list is shown in Ta . ble 3-4

Table 3-4. 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 miniLAB 1008 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 miniLAB 1008, 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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