Omega OMB-DAQ-2408 Series, Руководство пользователя

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OMB-DAQ-2408 Series User's Guide Functional Details
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Refer to Figure 4 on page 12 for the location of the DIFF inputs.
When connecting DIFF voltage inputs to a "floating" voltage source, make sure there is a DC return path from
each voltage input to ground. You make this path by connecting a resistor from each low channel input to an
AGND pin. A value of approximately 100 kΩ can be used for most applications. This does not apply to
channels configured for TC input, as they have their own internal reference.
Leave unused input channels either floating or tied to an AGND terminal.
Source impedances should be kept as small as possible to avoid settling time and accuracy errors.
Figure 6 shows a DIFF voltage connection using a ground path resistor.
Figure 6. DIFF voltage connection with ground path resistor example
Gain queue
Use the OMB-DAQ-2408 Series channel - gain queue feature to configure a list of channels, modes, and gains
for each scan. The settings are stored in a channel – gain queue list that is written to local memory on the
device.
The channel - gain queue list contains one or more channel numbers and range settings. You can configure up to
64 elements. The channels can be listed in any order, and can include duplicate channels for sampling at
different ranges.
An example of a 12-element list is shown in the table below.
Sample channel gain queue list
Element Channel Range
0 CH0 BIP10V
1 CH1 BIP5V
2 CH0 BIP2Pt5VOLTS
3 CH4 BIP2Pt5VOLTS
4 CH8 BIP2Pt5VOLTS
5 CH0 BIP5V
6 CH1 BIP1Pt25VOLTS
7 CH7 BIP5V
8 CH0 BIP1Pt25VOLTS
9 CH15 BIP10V
10 CH9 BIP1Pt25VOLTS
11 CH10 BIP2Pt5VOLTS
Carefully match the gain to the expected voltage range on the associated channel or an over range condition
may occur. Although this condition does not damage the device, it does produce a useless full-scale reading,
and can introduce a long recovery time due to saturation of the input channel.
CH0H
CH0L
AGND
CH1H
CH1L
AGND
100 k
Ω
–
+