LED indication

This article contains the description of LED indication, all device states and a device startup simulator.

Neuron

Label Function Meaning Colour
PWR On Supply voltage indication Red
RUN Blinking Microprocessor I/O status indication Green
Digital inputs (DI) On Indication of log.1 at the input Green
Digital outputs (DO) On Output switch indication Green
Realy outputs (RO) On Relay switch indication Green
TX (RS485) On Indication of serial line broadcasting Green
RX (RS485) On Indication of serial line receiving Green
User LEDs Selectable Freely programmable user LEDs Green
ETH On
Off
Blinking
Off
Connection established
Connection not established
Communication in progress
Connection not established
Yellow

Green

The following chapters describe all LED states for the Unipi Neuron controller:

  • Normal startup
  • Standard functions - communication via serial lines, DirectSwitch, MasterWatchDog
  • FW update on I/O boards

Next to the state description is a picture showing the status of LED indicators.

Some states can have several meanings and can mean e.g., a computer module error, defective SD card or an inappropriately chosen method of communication. You will find everything in the description of individual states.

All LEDs are off

State: Power-Off

The controller power supply is unplugged. If the PWR LED does not change its state on the controller even after connecting the power supply, try another power supply. If the state does not change after replacing the power supply, it is likely that the controller has been damaged. In this case, please contact technical support.

PWR is On

State: Power-On

The controller is powered. If the controller remains in this state longer than a minute without change, it is possible that it is damage. In this case, please contact technical support.

State: Does not communicate with I/O

RUN LED:
ON: 2000ms / OFF: 2000ms

If communication with I/O is not required and the web page of the controller can be displayed, or the device responds to the response test (ping), this is a regular operating state.

By default, this state is indicated when the program in the controller is not communicating with the I/O board. The state, for M and L controllers, is indicated for each section separately by means of a RUN LED with the corresponding marking (RUN1, RUN2, RUN3).

Because the default program in the controller does not communicate with I/O, it is also the default state when starting the device after inserting an SD card with a newly flashed OS.


If this state is indicated, the LEDs on the ETH connector are not emitting or blinking, and/or the controller cannot be found in the network, there may be a fault in the SD card. Try replacing the SD card with the newly flashed OS. If this doesn't help either, please contact technical support.

State: Communicates with I/O

RUN LED:
ON: 2000ms / OFF: 50ms

The main computing module (Raspberry Pi) communicates with the input and output (I/O) board of the given section. Communication can take place via Modbus TCP server, SysFS method, file entry or using API EVOK.

By default, this status is indicated when a program in the controller is running and communicating with the I/O section.

State: RS485 traffic

TX/RX LED:
randomly blinking

The program in the controller communicates via a serial line RS485.

DirectSwitch function

The DirectSwitch function is implemented directly in the microprocessor of the I/O section and is therefore independent of the control SW i.e., also of communication with inputs and outputs. You can read more about this function in the article about description of inputs and outputs. The function can be configured in one of three modes, their short description and illustrative LED indication can be found below:

DirectSwitch Copy

Input state is copied to the output.

DirectSwitch Inverse-copy

Negated state of the input is set on the output.

DirectSwitch Toggle

If a rising edge is detected on the input, the output state is negated.

Master Watchdog

If the function is enabled on the microprocessor of the given section, the processor continuously monitors the communication from the computing module. If no commands are detected during the set time, the section processor automatically restarts and sets the saved default configuration. You can read more about this function in the article about description of inputs and outputs.

I/O board firmware update

When flashing FW I/O board, all LEDs in the top and bottom row are On, except for every fourth. LEDs that are not fitted are also included in this rule.

Completion of the update is indicated by turning On every second LED and subsequent restart of the I/O section is indicated by turning On all LEDs, including RUN.

Below we provide a controller startup simulator, where you can see the entire process from plugging in power to startup. The simulation can be started by pressing the “​Plug in power​​” button below the controller image.

Observe the RUN LED during startup. After plugging in the power supply, the OS bootloader “uboot” starts first, this state is indicated by the first longer turn On of the diode. After a while, the OS will start.


Startup without I/O communication:
The controller is ready if the RUN LED blinks constantly slowly.

Behaviour description Meaning Off On
PWR is on, RUN is on with short blinks OS is running but not communicating with I/O board 2000ms 2000ms

Plug in power


Startup with the program, including communication with I/O:
The controller is ready if the RUN LED is continuously On with short blinks.

Behaviour description Meaning Off On
PWR is on, RUN is on with short blinks OS is running a commundnicating with I/O board 50ms 2000ms

Plug in power