Measurement Computing USB-231-OEM, User Manual, Page: 11 / 26

USB-231-OEM User's Guide Functional Details
11
Single-ended mode pinout
Do not connect to connector pins labeled NC .
J2 single-ended pinout
Pin Signal name Pin description Pin Signal name Pin description
1 AOUT0 Analog output 0 2 AOUT1 Analog output 1
3 AGND Analog ground 4 AGND Analog ground
5 CH3H Analog input 3 6 CH3L Analog input 7
7 CH2H Analog input 2 8 CH2L Analog input 6
9 CH1H Analog input 1 10 CH1L Analog input 5
11 CH0H Analog input 0 12 CH0L Analog input 4
13 AGND Analog ground 14 AGND Analog ground
15 D– USB differential data signals 16 VBUS USB power
17 D+ USB differential data signals 18 LED Status LED driver
19 GND Digital ground 20 DIO0 DIO bit 0
21 DIO1 DIO bit 1 22 DIO2 DIO bit 2
23 DIO3 DIO bit 3 24 DIO4 DIO bit 4
25 DIO5 DIO bit 5 26 DIO6 DIO bit 6
27 DIO7 DIO bit 7 28 NC No connection
29 TRIG Digital trigger input 30 NC No connection
31 NC No connection 32 GND Digital ground
33 CTR Counter input 34 +VO User voltage output
Signal connections
Analog input
You can connect up to eight single-ended inputs or up to four differential inputs to connectors
CH0H/CH0L
through
CH3H/CH3L
. The input voltage range is ±10 V. Figure 3 shows the USB-231-OEM analog input
circuitry.
Figure 3. USB-231-OEM analog input circuitry
The main analog input circuitry blocks are as follows:
 MUX
—The multiplexer (MUX) routes one AI channel at a time to the mode selector multiplexer
(DIFF/SE MUX).

DIFF/SE MUX
—The mode selector MUX selects between DIFF mode and SE measurement mode.
 IA
— The instrumentation amplifier (IA) removes the common mode signal and buffers the analog input
signal before it is sampled by the analog-to-digital converter (ADC).

ADC
—The ADC digitizes the AI signal by converting the analog voltage into digital code.