Digital I/O Connections; Digital Input Signal Connection (Ttl Di/O, Pull-Up) - Advantech USB-4751 User Manual

3.3

Digital I/O Connections

3.3.1

Digital Input Signal Connection (TTL DI/O, Pull-Up)

A digital input/output (DI/O) channel can be configured by software to perform digital
input measurement, which is the power-on default configuration, or digital output
generation. When performing digital input measurement, the voltage logic level
between the digital input (DI) terminal and the digital ground (DGND) terminal is mea-
sured. To prevent undetermined or fluctuating results when input is floating, the digi-
tal input channel is internally pulled-up. This is shown in Figure 3.3.
Figure 3.3 Digital input signal connection
11 USB-4751/4751L User Manual