Advantech PCIE-1805, Руководство пользователя

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PCIE-1805 User Manual 18
3.3.2 Measurement Mode Selection
Current Measurement Setting (SW2 & SW3)
PCIE-1805 provides a function current measurement of ranging 0-20mA or 4-20mA
for users to choose from. To use this function, you should follow below procedure:
1. Set corresponded current measurement channel on SW2 and SW3 (Voltage:
OFF, Current: ON)
2. Set the channel to differential
3. Set the value range to 0-20mA or 4-20mA
3.3.3 Analog Input Connections
PCIE-1805 supports 32 single-ended analog inputs and 16 differential inputs.
Differential Channel Connections
The differential input channels operate with two signal wires for each channel, and
the voltage difference between both signal wires is measured.
If one side of the signal source is connected to a local ground, the signal source is
ground-referenced. Therefore, the ground of the signal source and the ground of the
card will not be exactly the same voltage. The difference between the ground volt-
ages forms a common-mode voltage (Vcm).
To avoid the ground loop noise effect caused by common-mode voltages, you can
connect the signal ground to the Low input. Figure 3-3 shows a differential channel
connection between a ground reference signal source and an input channel on the
PCIE-1805. With this connection, the PGIA rejects a common-mode voltage Vcm
between the signal source and the PCIE-1805 ground, shown as Vcm in Figure 3-4.
NA - 2 Reserved
NA - 3 Reserved
NA - 23 Reserved
NA - 24 Reserved
NA - 25 Reserved
SW2
Switch No. Channel Switch No. Channel
1 CH0 & 1 5 CH8 & 9
2 CH2 & 3 6 CH10 & 11
3 CH4 & 5 7 CH12 & 13
4 CH6 & 7 8 CH14 & 15
SW3
1 CH16 & 17 5 CH24 & 25
2 CH18 & 19 6 CH26 & 27
3 CH20 & 21 7 CH28 & 29
4 CH22 & 23 8 CH30 & 31