What does the Red LED labeled ERR blinking or flashing on the M241 PLC mean?
The Red LED labeled ERR is blinking/flashing on M241 series PLC. What does it mean?
M241 PLC (TM241C24R, TM241C24T, TM241C24U, TM241C40R, TM241C40T, TM241C40U, TM241CE24R, TM241CE24T, TM241CE24U, TM241CE40R, TM241CE40T, TM241CE40U, TM241CEC24R, TM241CEC24T, TM241CEC24U)
M241 LED physical indicator light
There are three types of ERR LED blinking:
Regular flash -
The LED turns on for 500ms and then off for 500ms regularly.
This signifies an INVALID_OS controller state There is not a valid firmware file present in the flash memory. The controller does not execute the application. Refer to the Firmware Upgrade section of the SoMachine HTML Help to restore a correct state.
Single flash -
The LED turns on for 1000ms, then off for a short 200ms and repeats this pattern.
This signifies an EMPTY controller state, no program has been loaded to the PLC in this state (usually after a Firmware Upgrade procedure has been done or when a Reset Origin is performed)
Fast flash -
The LED flashes on and off alternating quickly within 500ms at a regular pace.
This signifies an EMPTY after a system error detected controller state.
This state is the same as the normal EMPTY state. But the application is present (as a BOOT project), and is intentionally not loaded into working memory. A next reboot (power cycle), or a new application download, will restore correct state.
For more information, please refer to the SoMachine HTML Help in the section:
Logic Controllers -> M241 Logic Controller -> Programming Guide -> Controller States and Behaviors -> Controller States Description