The MonoDAQ U-X is capable of receiving 5V digital inputs on all eight channels. This is commonly used for monitoring digital outputs of other controllers and logging states of components like solenoids, lights, etc..
The Digital Input will be HIGH if the voltage on the Digital Input pin exceeds ? V.
Unlike analog inputs, multiple digital inputs can be set up and without affecting the sample rate. All eight channels can be acquiring data simultaneously at the device’s maximum sample rate (1 or 50kSPS).
Digital inputs can also be used to add external controls to the U-X like switches and buttons which can be used as triggers in the X3 software.
Monitoring other devices
The digital input pin on the U-X is connected to the digital output of the device we are monitoring.
In this example, the U-X is monitoring a microcontroller output pin which is powering a LED.
The digital inputs are w.r.t GND so the ground pins of both devices are connected.
The resistor limits the maximum current that can be drawn by the LED and only serves to protect the microcontroller.
Whenever the microcontroller turns ON the LED the U-X will detect it as a HIGH Digital Input.
Adding external controls to the U-X
A convenient way to connect external buttons/switches to the U-X is by using its internal power supply
They can be used for adding controls for custom measuring devices, modifying running math calculations and countless other functionalities.
The EXC pin is set to 5 V excitation and connected to the switch. Whenever the switch is closed the Digital Input goes HIGH.
The 10k pull-down resistor must be used to prevent the Digital Input pin from floating whenever the switch is open.
Up to eight switches can be connected in this way though. Every input needs to have its own pull-down resistor.
If the internal power supply is not available (being used for some other function) an external voltage source needs to be used.
In the example, a battery is shown but any voltage source between ? V and ? V can be used.