SSH access

All Unipi devices include a full-featured ARM-based Linux environment, which is accessible via a Secure Shell console after following the steps below. This allows the users of Unipi devices to fully leverage the incredible versatility provided by open-source software packages.

Axon
Neuron
Unipi 1.1

Unipi Axon includes an internal SSH server which is disabled by default and must be enabled according to the instructions in the “Getting Started” leaflet packaged with the device. After the server is enabled it is possible to connect to the device via any SSH client in the local network. This guide is intended to help users who are not otherwise familiar with SSH and is not necessarily the only way of connecting to the device.

Connecting to the service interface, enabling the SSH

The first step is to enable remote access to the SSH internal server. This configuration is available in the Axon service interface accessible by the following methods:

1) In a local network (with DHCP):

  1. Connect the PLC to your local network, plug in the power supply and wait at least for a minute before the PLC boots and gets an IP address from DHCP. After that unplug the power supply
  2. Press and hold the Reset button located in the upper row of connector labels (left from USB port labels)
  3. Plug in the power supply. After few moments the controller will switch to the service mode indicated by alternating blinking of the upper and lower row of LEDs. You can release the Reset button.
  4. You now need to get the PLC's IP address. You can obtain it either from the DHCP server or using a suitable application such as Advanced IP Scanneruser manual

2) Direct connection to the PLC (without DHCP):

  1. Connect to the PLC using a network cable (RJ45)
  2. Press and hold the Reset button located in the upper row of connector labels (left from USB port labels)
  3. Plug in the power supply. After few moments the controller will switch to the service mode indicated by alternating blinking of the upper and lower row of LEDs. You can release the Reset button.
  4. Set the PC's IP address to 192.168.200.100, mask 255.255.255.0
  5. The Axon's IP is now set to 192.168.200.200

3) Via a Wi-Fi hotspot

  1. Press and hold the Reset button located in the upper row of connector labels (left from USB port labels)
  2. Plug in the power supply. After few moments the controller will switch to the service mode indicated by alternating blinking of the upper and lower row of LEDs. You can release the Reset button.
  3. Connect to Wi-Fi network with SSID: UNIPICONFIG, using unipi.technology as password. Wait until your PLC obtains an IP address from the DHCP server running in the PLC
  4. The Axon's IP is now set to 192.168.201.1

Enter the IP address into your browser's address tab and confirm. Upon loading the service interface the following screen with multiple buttons should appear:

To enable SSH click on Enable SSH in the middle of the screen and then click on Restart System in the upper right corner.

All up-to-date OS images provided for Unipi Neuron and Unipi 1.1 controllers have SSH enabled by default except for the Mervis OS image. To enable SSH in Mervis OS create a new empty file named ssh (without any suffix, or with *.txt* suffix) and place it into the microSD card's boot directory along with Mervis OS. The SSH server will start after re-inserting the SD card into the PLC

There are many tools which can be used to connect to SSH servers. For this tutorial, we recommend using PuTTY

Communication via SSH using PuTTY

For using SSH you need to know the target PLC's IP address. To detect the address you can follow this guide: Detecting the PLC's IP address.

To connect to the PLC we will use the PuTTY. You can use other SSH applications as well, but PuTTY is the most suitable for Windows OS. The program can be downloaded in the Useful tools.

Install the downloaded PuTTY following the installer's instructions. After that, launch the program through putty.exe (its default location is C:/Program Files/PuTTY).

Upon launching the following window will be displayed:

Enter the IP address into the Host Name tab and check if the Connection type is set to the controller's SSH. Then click on Open. A security dialogue window will appear for the first time. Click on “Yes” to display the SSH terminal's command line.

The next step is to enter your login:

  • Login: unipi
  • Password: unipi.technology


Login has a time limit. If the limit expires, login will be no longer possible and you need to restart PuTTY and log in again.

The password is entered as an invisible text, eg. if the cursor does not move when entering the password, it is not an error!

After a successful login to a Unipi PLC this screen will appear:

Upon finishing the configuration you need to disable the SSH access or change the user password!

Changing the SSH access password:

User password can be changed using the passwd command.

unipi@S103-sn16:~$ passwd

After entering the passwd command a prompt for entering current password will appear. The next step is to enter the new password and then re-enter it for confirmation.

Changing password for unipi.
Current password:
New password: 
Retype new password:
passwd: password updated successfully