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OM-USB-5203 User's Guide
Sensor Connections
10
Do not connect two different sensor categories to the same channel pair
The OM-USB-5203 provides a 24 bit A/D converter for each channel pair. Each channel pair can monitor one
sensor category. To monitor a sensor from a different category, connect the sensor to a different channel pair
(input terminals).
CJC sensors
The OM-USB-5203 has two built in high-resolution temperature sensors. One sensor is located on the right side
of the package, and one sensor is located on the left side.
Current excitation output terminals (±I1 to ±I4)
The OM-USB-5203 has four dedicated pairs of current excitation output terminals (±
I1
to ±
I4
). These terminals
have a built-in precision current source to provide excitation for the resistive sensors used for RTD and
thermistor measurements.
Each current excitation terminal is dedicated to one pair of sensor input channels:
I1+ is the current excitation source for channel 0 and channel 1
I2+ is the current excitation source for channel 2 and channel 3
I3+ is the current excitation source for channel 4 and channel 5
I4+ is the current excitation source for channel 6 and channel 7
Four-wire, two sensor common terminals (4W01 to 4W67)
These terminals are used as the common connection for four-wire configurations with two RTD or thermistor
sensors.
Two sensor common terminals (IC01 to IC67)
These terminals are used as the common connection for two-wire configurations with two RTD or thermistor
sensors.
Digital terminals (DIO0 to DIO7)
You can connect up to eight digital I/O lines to the screw terminals labeled
DIO0
to
DIO7
. Each terminal is
software-configurable for input or output.
If a digital bit is set up as an alarm, the bit is configured for output on power-up, and assumes the state defined
by the alarm configuration.
Power output terminals (+5V)
The two
+5V
output
terminals are isolated (500 VDC) from the USB +5V.
Caution!
Each +5V terminal is an output. Do not connect to an external power supply to these terminals or
you may damage the OM-USB-5203 and possibly the computer.
Ground terminals (GND)
The six ground terminals (
GND
) provide a common ground for the input channels and DIO bits, and are isolated
(500 VDC) from the USB GND.