![]() Figure 4 shows the external connections for the measurement as well as the pinouts for the NI 9217 RTD module. The two additional leads from a 2-wire RTD increase the attainable accuracy. Connect the black (or white) leads on the negative side of the resistive element to the excitation and channel negative on the DAQ device. To connect this RTD, simply connect each of the red leads on the positive side of the resistive element to the excitation positive and channel positive on the DAQ device. 3-Wire RTD Measurement 4-Wire RTD Signal Connection The excitation positive is connected to RTD0+ because the NI 9217 internally connects this to the excitation terminal.įigure 3. Connect one of the black (or white) RTD leads to excitation negative and the other to channel negative.įigure 3 shows the external connections for the measurement as well as the pinouts for the NI 9217 RTD module. Place a jumper from the excitation positive pin to the channel positive on the DAQ device (Note: This step is not necessary with the NI 9217 it internally connects these two channels, see Figure 3). The NI 9217 analog input module does not support 2-wire measurement configurations.Ĭonnect the red RTD lead to the excitation positive. The easiest way to take a temperature reading with an RTD is using the 2-wire method however, the disadvantage of this method is that if the lead resistance in the wires is high, the voltage measured, VO, is significantly higher than the voltage that is present across the RTD itself. In the 2-wire method, the two wires that provide the RTD with its excitation current and the two wires across which the RTD voltage is measured are the same. ![]() Place a jumper from the excitation negative to the channel negative on the DAQ device. Connect the black (or white) RTD lead to the excitation negative. Place a jumper from the excitation positive pin to the channel positive on the DAQ device. The next step is to physically connect the RTD to your DAQ device.Ĭonnect the red RTD lead to the excitation positive. AI x (+/-): Some devices may refer to AIx+ and AIx- instead.RTD x (+/-): Most NI RTD hardware refers to RTD x+ and RTD x- terminals for each differential measurement channel, where x refers to the channel number.The following terminal types correspond with RTD measurements:
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