Chapter 3.5 on page 26 of the user manual says that there are 3 ways to interface with the VN100. (2 different serial types, and SPI). SPI would be useful if you were interfacing with another microcontroller, but not so much for your computer.
Serial port 1 is "regular" RS232 logic levels. Which is +-12 Volts. If your computer has a serial port, you can use that.
Serial port 2 has 3 volt logic levels. For this, you should use a FTDI cable. For example: https://www.digikey.com/product-detail/en/ftdi-future-technology-devices-international-ltd/TTL-232RG-VREG3V3-WE/768-1071-ND/2441361
RS232 has many control wires, but you probably only need 4: V+, GND, RX, and TX. Remember to connect the computer's RX line to the devices TX line, and vice-versa.
Then use a serial terminal emulator such as picocom or minicom to interface with your device. Here is an example:
> picocom -b 9600 /dev/ttyUSB0
(control-a, control-x to exit)
you probably have to put your user in the "dialout" or "tty" groups too.