NI PXI-2501/2503 1-Wire 48×1 Multiplexer Topology

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Edition Date: April 2015

Part Number: 375472H-01

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When using the NI PXI-2501/2503 as a 1-wire 48×1 multiplexer, connect your signals using the NI TB-2605 terminal block. The following figure is a representation of the NI PXI-2501/2503 in this mode.

Making a Connection

In 1-wire mode, all channels can connect to COM0+. COM0– is always connected to 1_WIRE_LO_REF and can optionally be used to route the second wire of a different signal (for example, the LO terminal of a DMM) through the switch.

During scanning, an example scan list entry is ch2->com0;. This entry routes the signal connected to 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+. 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 1-wire 48×1 multiplexer topology.

Caution  Do not connect to RESERVED pins.


Software Name Hardware Name
NI PXI-2501/2503
Connector Pin Number
NI TB-2605
Terminal Name
ch0 67 CH0
ch1 66 CH1
ch2 65 CH2
ch3 64 CH3
ch4 63 CH4
ch5 62 CH5
ch6 59 CH6
ch7 58 CH7
ch8 57 CH8
ch9 55 CH9
ch10 54 CH10
ch11 53 CH11
ch12 50 CH12
ch13 49 CH13
ch14 48 CH14
ch15 47 CH15
ch16 46 CH16
ch17 45 CH17
ch18 40 CH18
ch19 39 CH19
ch20 38 CH20
ch21 37 CH21
ch22 36 CH22
ch23 35 CH23
ch24 33 CH24
ch25 32 CH25
ch26 31 CH26
ch27 30 CH27
ch28 29 CH28
ch29 28 CH29
ch30 25 CH30
ch31 24 CH31
ch32 23 CH32
ch33 21 CH33
ch34 20 CH34
ch35 19 CH35
ch36 16 CH36
ch37 15 CH37
ch38 14 CH38
ch39 13 CH39
ch40 12 CH40
ch41 11 CH41
ch42 6 CH42
ch43 5 CH43
ch44 4 CH44
ch45 3 CH45
ch46 2 CH46
ch47 1 CH47
1wire 22 1wireREF
com0 61 COM0+
27 COM0–
ab0 52 AB0+
18 AB0–
No Connect1 60 COM1+
26 COM1–
No Connect1 44 COM2+
10 COM2–
No Connect1 43 COM3+
9 COM3–
No Connect1 51 AB1+
17 AB1–
1 Not used in this topology

Additional Pin References

NI PXI-2501/2503
Connector Pin Number
Signal name
7, 56 GND
68 CJS+
34 CJS-


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