In the EEROS library you will find a directory with examples. For this example see HalTest4.cpp.

The system either uses real hardware inputs and output or makes use of a simulated gpio device. You need to install the necessary wrapper library for gpio, see Installing Hardware Libraries.

When using a simulated gpio device, make sure to load the kernel driver first and then create the device with

$ sudo modprobe gpio-sim
$ sudo mkdir /sys/kernel/config/gpio-sim/ofagpio 
$ sudo mkdir /sys/kernel/config/gpio-sim/ofagpio/bank0
$ echo 32 | sudo tee /sys/kernel/config/gpio-sim/ofagpio/bank0/num_lines
$ echo 1 | sudo tee /sys/kernel/config/gpio-sim/ofagpio/live

Make sure that your local user has access to the device file.

$ sudo chown $USER:$USER /dev/gpiochip0

Open a shell in the build directory of your EEROS library and run

$ ./examples/hal/halTest4 -c HalTest4ConfigGpio.json  

It will start in safety level slOne and mirror the digital input channel 1 to output channel 0. You can check this behavior with

$ echo pull-up | sudo tee /sys/devices/platform/gpio-sim.0/gpiochip0/sim_gpio1/pull

or

$ echo pull-down | sudo tee /sys/devices/platform/gpio-sim.0/gpiochip0/sim_gpio1/pull

while reading the state of channel 0 with

$ cat /sys/devices/platform/gpio-sim.0/gpiochip0/sim_gpio0/value