Measurement-computing USB-2404-UI Manuale Utente Scaricare il pdf (Pagina 11)

USB-2404-UI User's Guide Functional Details

 Connect the positive signal of the signal source to the positive input signal terminal (HI).

 Connect the negative signal of the signal source to the negative input signal terminal (

LO).

 Connect to the excitation terminals (

EX+/EX–)-if the sensor requires a separate excitation connection.

The spring terminal assignments for each input mode are listed in the following table.

6-position spring terminal assignments per input mode

Terminal

Voltage

Current

Bridge Resistance RTD

Full Half Quarter 2-wire 4-wire 4-wire 3-wire

3 — HI EX+ EX+ HI EX+ EX+

4 HI — HI HI — HI —

5 LO LO EX– EX– LO EX– EX–

6 — — LO LO — LO LO

Refer to "USB-2404-UI circuitry" on page 13 for information about connections in each mode.

Strain relief slot

Use the strain relief slot to keep the USB cable from disconnecting from the device inadvertently. Feed a tie

wrap through the slot and secure to the USB cable when it is connected to the device.

USB connector

The USB connector provides +5 V power and communication. The voltage supplied through the USB connector

is system-dependent, and may be less than 5 V. No external power supply is required.

LED

The LED indicates the device status. When connected to a USB port, the LED blinks steadily to indicate that

the device is initialized and receiving power. Refer to the following table for the possible LED states.

LED state/device status

LED state Device status

Not lit The device is not connected to a USB port or hub.

Continuous single-blink The device is operating normally.

Continuous double-blink The device is operating normally. (Connected to a USB 1.1 port or hub.)

Connecting wires to the spring terminals

Use a flathead screwdriver with a blade smaller than 2.3 x 1.0 mm (0.09 x 0.04 in.) to connect wires to the

detachable spring terminal connectors. Use 18 to 28 AWG copper conductor wire with 7 mm (0.28 in.) of

insulation stripped from the end when wiring connections.

Insert the screwdriver into the spring clamp activation slot and press a wire into the corresponding connector

terminal, then remove the screwdriver to clamp the wire into the terminal.

Figure 4. Connecting a wire to the spring terminal connector

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