How to Access the Serial Shell on a JACE (JACE 8000 and JACE 9000)

Connect a USB cable to the JACE's debug port, open a terminal at 115200 baud, 8-N-1, and log in with platform credentials to reach the system shell.

The serial shell is the engineer's back door into a JACE. When the controller is on an unknown IP address, when its network settings are wrong, when the clock has jumped and Niagara will not start, or when you need to reset lost platform credentials, the serial shell is how you get in without a network. This guide explains the hardware, the software settings, the difference between the system shell and shell mode, and what each can do.

When do you need the serial shell?

• The JACE's IP address is unknown, or it has been set to an address you cannot reach
• Network settings (IP, subnet, gateway) need correcting without a working network connection
• The system date or time is wrong and is stopping Niagara from starting or certificates from validating
• You need to reset lost platform credentials using shell mode
• You want to watch the boot process to diagnose a controller that will not start
• A factory reset needs to be monitored

What you need

Use a data cable, not a charge-only cable. Charge-only cables are a surprisingly common reason for "nothing happens".

Step 1: Connect the cable and find the COM port

1. Connect the cable between the JACE's debug port and your PC.
2. The PC detects a USB serial device and installs a driver. Windows normally does this automatically.
3. Open Device Manager (Windows key + R, type devmgmt.msc) and expand Ports (COM & LPT).
4. Note the COM port number assigned to the JACE's USB serial device, for example COM5.

If no new COM port appears, try another cable or USB port, and check that the JACE is powered.

Step 2: Configure the terminal

In PuTTY:

1. Under Connection > Serial, set:
   • Serial line: your COM port (e.g. COM5)
   • Speed (baud): 115200
   • Data bits: 8
   • Stop bits: 1
   • Parity: None
   • Flow control: None
2. Under Session, select connection type Serial and click Open.

In Tera Term, choose Serial, select the COM port, then Setup > Serial port and enter the same settings.

Step 3: Log in to the system shell

Press Enter once or twice. A login prompt appears. Log in with the JACE's platform username and password. On a factory-fresh JACE 8000 these are tridium / niagara; on a commissioned controller use the credentials set at commissioning (see JACE default credentials).

After logging in you see the system shell menu. It is a simple numbered menu, not a general command line, and its options typically let you:

• display and update network settings (IP address, subnet mask, gateway, DNS) for each Ethernet port
• display and set the system date and time
• ping another host to test connectivity
• change the current user's password
• enable or disable certain services
• reboot the controller
• log out

Exact options and numbering vary by model and Niagara version; read the menu on screen before choosing.

System shell vs shell mode

There are two different shells, and it is important not to confuse them:

If you have lost the platform credentials, you cannot log in to the system shell, so use shell mode. It shows the Host ID, a token and the OS version, which your distributor sends to Tridium to obtain a reset key. See how to generate a platform reset token.

Common tasks in the serial shell

Find or change the JACE's IP address

Choose the network settings option, read the current configuration, and enter new values for the interface you need. Save and reboot if prompted. Then set your laptop to the same subnet and connect with Workbench.

On a JACE 9000 with both Ethernet ports configured, set a default gateway on the first interface (en0) only and leave the second (en1) blank. Linux keeps only the first default route it reads at boot, so a gateway on both ports causes traffic on one port to be silently dropped on its way back.

Fix the system date and time

If the clock is wrong, certificates may be rejected and, on some older JACE 8000 software, Niagara may fail to start. Use the date/time option to set the correct date and time, then reboot. For the specific problem of older JACE 8000s that will not boot after a factory reset, see restoring connectivity on older JACE 8000s.

Watch the boot sequence

With the terminal connected, reboot the controller. The console shows the operating system and Niagara starting, which helps diagnose controllers that hang, reboot repeatedly or fail to start a station.

Reboot safely

Use the menu's reboot option rather than removing power, particularly while the controller is writing to storage.

Using other terminal programs

PuTTY is the most common choice on Windows, but any serial terminal works:

• Tera Term (Windows): File > New connection > Serial, choose the port, then Setup > Serial port for 115200, 8, none, 1, none.
• macOS: find the device with ls /dev/tty.usb*, then connect with screen /dev/tty.usbserial-XXXX 115200. Exit with Ctrl-A then K.
• Linux: find the device (usually /dev/ttyUSB0 or /dev/ttyACM0) and connect with screen /dev/ttyUSB0 115200 or minicom. Add your user to the dialout group if you get a permissions error.

Enable logging in your terminal (PuTTY: Session > Logging) so you have a record of boot messages and any tokens or settings displayed.

Reading the boot output

With the terminal connected before power-up, you see the controller start. Learning what a normal boot looks like on a healthy unit makes faults easier to spot:

• the bootloader starts and shows the alternate boot options prompt (this is where ESC enters shell mode)
• the operating system loads and brings up network interfaces
• the Niagara daemon starts
• the station starts, which can take several minutes on a large station

If output stops at the same point on every boot, note the last messages: they usually identify the failing component, for example a storage error, a date problem or a module that cannot load. Send the log to support with the controller's Niagara version.

Field kit for JACE work

Keep these in every engineer's bag:

• a known-good micro-USB data cable (JACE 8000) and USB-C data cable (JACE 9000)
• a laptop with PuTTY or Tera Term installed and USB serial drivers working
• an Ethernet cable and, ideally, a small unmanaged switch
• a note of 192.168.1.140 and a spare static IP for the laptop
• the site's platform credentials from your password vault
• the latest station backups and Niagara Workbench versions for the sites you support

Troubleshooting

No COM port appears. Charge-only cable, faulty cable, missing driver, or the JACE is not powered. Try another data cable and USB port.

The terminal opens but shows nothing. Press Enter. If still blank, check the baud rate (115200) and that you selected the right COM port. Reboot the JACE with the terminal open to see boot messages.

Garbled characters. The baud rate or data settings are wrong.

Login rejected. You are using station credentials instead of platform credentials, or the platform credentials were changed at commissioning. Use shell mode to reset them.

The ESC prompt flashes past. Press ESC repeatedly from the moment the controller starts rebooting; the prompt is shown only briefly.

Changes do not take effect. Some changes require a reboot. Confirm the setting was saved before rebooting.

Record what you change

Changes made in the serial shell are easy to forget because they happen outside Workbench and the station. Each time you use it:

• note the date, time and reason in the site log
• record old and new values for any network setting you change (IP address, mask, gateway, DNS)
• record any date or time correction and why it was needed
• save your terminal log with the site documentation

This matters most when several engineers or companies work on the same site: an undocumented IP change is one of the most common causes of "the JACE has disappeared" calls.

When to call support

Contact your distributor's technical support if:

• the boot output stops at the same point every time and you cannot identify the cause
• the controller reports storage errors
• shell mode does not offer the option you need for your Niagara version
• you need a platform credential reset key

Have the controller's model, Host ID (if available), Niagara version and a copy of the terminal log ready. For controllers supplied by Tyrrell Products, our support team can help.

Security notes

The debug port gives powerful access to anyone with physical access to the controller. Install JACEs in locked panels or plant rooms, keep platform credentials strong and unique, and record who has them. Shell-mode credential resets require Tridium to validate a token, which prevents someone with only physical access from silently taking over a controller.

Frequently asked questions

What baud rate does the JACE 8000 serial shell use?

115200 baud, 8 data bits, no parity, 1 stop bit, no flow control.

Which port is the debug port on a JACE 8000?

The micro-USB port labelled Debug. On a JACE 9000 it is the USB Type-C debug port.

What is the default serial shell login?

On a factory-fresh JACE 8000, tridium / niagara. On a commissioned controller, use the platform credentials set at commissioning.

Can I reset platform credentials from the serial shell?

Not from the logged-in system shell. Reboot into shell mode by pressing ESC at the boot prompt, then choose 8 – Reset Platform Credentials.

Can I change the JACE IP address without Workbench?

Yes. Use the network settings option in the system shell over the debug port.

Do I need special drivers for the JACE debug port?

Usually not; Windows normally installs a USB serial driver automatically when the cable is connected. If no COM port appears, check the cable is a data cable and try another USB port before installing drivers.

Can I use the serial shell while the station is running?

Yes. The system shell runs alongside Niagara, so you can check network settings or ping hosts without stopping the station. Rebooting from the shell will, of course, restart everything.

Is the serial shell available on a JACE 9000?

Yes, through the USB Type-C debug port, with the same terminal settings.

Is it safe to leave the debug cable connected?

Disconnect it when you finish. A connected cable is a reminder of physical access to the controller, and panels should be closed and locked after work.

Can I use the serial shell to back up a JACE?

Backups are normally taken from Workbench over a platform connection. The serial shell is for network, time and recovery tasks.

Need help from a Niagara engineer?

If this guide has not solved the problem, contact the Tyrrell Products technical team on 01942 732819 or [email protected]. Tell us the controller or host type, its Niagara version and what you have already tried, and we will help you get the system running.

Related guides

• JACE default credentials
• How to generate a platform reset token
• Restoring connectivity on older JACE 8000s after a factory reset
• JACE FAQs