LED signals


SOMANET Circulo has several LEDs that show the servo drive’s state or indicate errors.


Please note that in the current revision the heatsink covers the LEDs completely.
All occuring errors are also reflected in the Error Report Object.
For your reference the position of the LED with the heatsink removed is given in the picture below.


Symbol Explanation
Constantly luminous
Single flashes (1 pulse per second)
Slow blinking (3 pulses per second)
Fast blinking (10 pulses per second)
Two colored behavior: One part of the LED is constantly luminous, the other is blinking slowly (3 pulses per second)
Two colored behavior: One part of the LED is constantly luminous, the other is blinking fast (10 pulses per second)

Core LED

The tri-color LED is used by the firmware to indicate internal status and errors. It provides an overview of the firmware state at a glance to quickly see whether a drive is operating nominally.


CiA 402 State
Not Ready to Switch On Switch on Disabled Ready to Switch On Switched On Operation Enabled Quick Stop Fault and Fault Reaction
EtherCAT State BOOT


Signals that are shown when the Bootloader is active:

Bootloader State No Fault
(firmware exists)
(no firmware exists)
Operation in progress


If your servo drive is running Bootloader v1.0 you may find the LED fading in rainbow colors indicating that the bootloader is active.

Drive LED

The four LEDs on the Drive module show Hardware Errors.

LED 1: Red LED 2: Red LED 3: Red LED 4: Green Explanation
No error
Watchdog ticks fault
Dead-time fault Phase A
Dead-time fault Phase B
Dead-time fault Phase C
Over-current in Phase A / Phase B / DC-bus
Over-voltage / Under-voltage / Over-temperature

Details about these errors and remedies can be found here: Error Report Object


Signals on the EtherCAT LED are required for EtherCAT conformity.

LED 1: RUN LED 2: ACT 0 LED 3: ACT 1
LINK is constantly showing a green light if there is a cable connected to either OUT or IN.

ACT is blinking when there are transmissions on either OUT or IN.

If none of the LEDs are active, check if the EtherCAT cables are connected properly.