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Přístup přes SSH

Všechny jednotky Unipi obsahují plně vybavené Linuxové prostředí na bázi ARM, ke kterému lze po provedení níže uvedených instrukcí přistupovat pomocí konzole Secure Shell. To umožňuje uživatelům Unipi plně využít obrovský potenciál otevřených softwarových balíků.

Proces povolení SSH se mezi jednotlivými řadami jednotek Unipi mírně liší. Pro jednotky Axon je postup uveden níže. U jednotek Unipi Neuron a Unipi 1.1 pak postupujte dle návodu pro počítače Raspberry Pi.

Kontroléry Axon disponují interním SSH serverem, který je ve výchozím stavu deaktivován a před jeho použitím je třeba jej spustit - instrukce k tomuto kroku naleznete v letáku dodávaném společně s jednotkou. Po povolení serveru je pak možné se k PLC připojit skrze jakéhokoliv SSH klienta v místní síti. Následující tutoriál je určen zejména pro uživatele, kteří nejsou s SSH obeznámeni, a nepředstavuje jediný možný způsob připojení.

Připojení k servisnímu rozhraní a povolení SSH

Prvním krokem je povolit vzdálený přístup k internímu SSH serveru. Toto nastavení je dostupné v servisním rozhraní Axonu, do kterého se dostanete následujícími způsoby:

1) In a local network (with DHCP):

  1. Connect the unit to your local network, plug in the power supply and wait at least for a minute before the unit boots and gets an IP address from DHCP. After that unplug the power supply
  2. Press and hold the Service button located (with exceptions) in the upper row of the connector labels to the left from USB port labels
  3. Plug in the power supply. After few moments the unit will switch to the service mode indicated by the slow flashing of all diodes in section 1 (except PWR and RUN)
  4. Now you can release the Service button.
  5. You now need to get the unit'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 unit (without DHCP):

  1. Connect to the unit using a network cable (RJ45)
  2. Press and hold the Service button located (with exceptions) in the upper row of the connector labels to the left from USB port labels
  3. Plug in the power supply. After few moments the unit will switch to the service mode indicated by the slow flashing of all diodes in section 1 (except PWR and RUN)
  4. Now you can release the Service button.
  5. Set the PC's IP address to 192.168.200.100, mask 255.255.255.0
  6. The Axon's IP is now set to 192.168.200.200

3) Via a Wi-Fi hotspot

  1. Press and hold the Service button located (with exceptions) in the upper row of the connector labels to the left from USB port labels
  2. Plug in the power supply. After few moments the unit will switch to the service mode indicated by the slow flashing of all diodes in section 1 (except PWR and RUN)
  3. Now you can release the Service button.
  4. Connect to Wi-Fi network with SSID: UNIPICONFIG, using unipi.technology as password. Wait until your unit obtains an IP address from the DHCP server running in the unit
  5. The Axon's IP is now set to 192.168.201.1

Vložte IP adresu do adresního řádku vašeho prohlížeče a potvrďte. Po spuštění servisního rozhraní by Vás měla uvítat obrazovka s několika tlačítky. Pro povolení SSH serveru nejprve klikněte na Enable ssh uprostřed obrazovky a poté na Restart System v pravém horním rohu.

U všech nejaktuálnějších obrazů OS, které pro naše jednotky poskytujeme je SSH ve výchozím stavu povoleno. Vyjímkou je však Mervis OS image, který má SSH vypnuto. Pro jeho aktivaci vytvořte soubor ssh (bez přípony, popř. *.txt) a tento prázdný soubor vložte do bootovacího oddílu SD karty s nachystaným Mervis OS.

Existuje široká škála nástrojů, pomocí kterých se lze k SSH serverům připojovat. Pro účely tohoto tutoriálu doporučujeme použít PuTTY.

Connect via SSH using PuTTY

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

To connect to the controller 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.

You must enable SSH before connecting to the controller.

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

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).

After launch, the following window will appear:

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.

A prompt to enter login and password will be displayed
The default login and password is:

  • 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:

Securing the OS (SSH)

Securing the operating system is always needed to prevent unauthorized access to the Unipi units. Using a non-secured OS may lead to unauthorized tampering that can stop or limit the system's operation. In the worst-case scenario, it may also cause damage to the connected technologies or endanger personnel on the installation site.

For these reasons, it is important to properly secure the system each time a new project is created. Alternatively, you can disable the SSH access completely.


As the connection is provided by the SSH protocol, it is necessary to know the IP address or the mDNS address of the device and have an SSH client installed on your PC or tablet. Among the most frequently used clients for Windows OS is the PuTTY application - user guide and default passwords are available here.

Before continuing, make sure you are logged in as the right user (for example “unipi” on our OpenSource OS). You can verify this by whoami command.

unipi@S103-sn999:~$ whoami
unipi

Now letps proceed to change the password by entering the following command:

passwd

A prompt to enter and confirm the current and new password will be displayed. If everything is set correctly, the following message will appear:

Changing password for unipi.
Current password:
New password:
Retype new password:

The entire process is depicted below (the password is not visible during its entering):

unipi@S103-sn999:~$ passwd
Changing password for unipi.
Current password:
New password:
Retype new password:
passwd: password updated successfully


Was the password change unsuccessful?
If the password change fails, the following message will appear:

passwd: Authentication token manipulation error
passwd: password unchanged

To solve this issue, try to enter the command below and then repeat the password change process.

sudo mount -rw -o remount /

Next, it's good practice to sync the changes on the storage (eMMC or SD card). This can be achieved by the sync command:

unipi@S103-sn999:~$ sync

You can now logout from your SSH session, reboot the PLC or power it of and on and login back to verify that the password has been sucesfully changed.

If the password cannot be changed even after entering the command, please contact our technical support.