|Download Help (Windows Only)|
When using the NI PXI-2501/2503 as a 2-wire dual 12×1 multiplexer, connect your signals using the NI TB-2605 terminal block. In this topology, you can connect to a Cold-Junction Sensor Channel for cold-junction compensation. The following figure is a representation of the NI PXI-2501/2503 in this mode.
The NI PXI-2501/2503 in this topology contains two banks of 12 2-wire input channels connected to a common 2-wire channel. These input channels are referred to as ch<0..23> and the two common channels are referred to as com0 and com2. You can only connect to the common channel that is in the same bank. The banks are organized as follows:
|Input Channels||Common Channel|
|ch0, ch1, ch2, ch3, ch4, ch5, ch6, ch7, ch8, ch9, ch10, ch11, cjtemp||com0|
|ch12, ch13, ch14, ch15, ch16, ch17, ch18, ch19, ch20, ch21, ch22, ch23||com2|
For example, you can connect ch5 to com0; however, you cannot connect ch5 to com2 in this topology. When connecting signals for ch5, you would connect them to CH5+ and CH5– for HI and LO of the signal, respectively. For com0, connect to COM0+ and COM0– for HI and LO of the signal, respectively.
Notice that in the first bank you can connect cjtemp to com0. This connects com0 to a temperature sensor on the NI TB-2605 terminal block. Refer to Cold-Junction Sensor Channel for more information.
During scanning, an example scan list entry is ch2->com0;. This entry routes the signal connected to CH2+ to COM0+ and the signal from CH2– to COM0–.
During immediate operations when calling the niSwitch Connect Channels VI or the niSwitch_Connect function with ch2+ and com0, the signal connected to CH2+ is routed to COM0+ and the signal connected to CH2– is routed to COM0–. To route the signals to AB0, use the niSwitch Connect Channels VI or the niSwitch_Connect function with com0 and ab0.
The following figure and tables identify the pins for the NI PXI-2501/2503 in the 2-wire dual 12×1 multiplexer topology.
|Caution Do not connect to RESERVED pins.|
|Software Name||Polarity||Hardware Name|
Connector Pin Number
|1 Not used in this topology|
Connector Pin Number