Questions Regarding EtherCAT Basic Functionality on i.MX RT1180 EVK with TwinCAT 3.1

[kejin-tan]

Dear Support Team,

I am currently debugging basic EtherCAT functionality on the i.MX RT1180 EVK in combination with TwinCAT 3.1, following the procedures outlined in the application note "Using TWINCAT3 in Run mode" and the README documentation provided with the SDK demo.

The EtherCAT state machine successfully reaches the OP state, but I have encountered the following issues:

Q1.
I can compile and load the evkmimxrt1180_ecat_digital_io_cm7 demo, and the state machine reaches OP as expected. However, the LED control does not work—the LEDs do not blink, and setting output states directly from TwinCAT has no effect. Is there any additional software configuration or hardware setup required to enable this digital I/O functionality?

Q2.
In the demo, which specific GPIO pin on the i.MX RT1180 chip is connected to the LED being controlled by the digital_io demo? I would like to verify the hardware mapping and ensure proper signal routing.

Q3.
I need to evaluate the timing accuracy of the SYNC0 and SYNC1 signals. However, after reviewing the i.MX RT1180 Reference Manual, User Guide, and Data Sheet, I could not find any information about external pins assigned to SYNC0/SYNC1. Are these signals not routed to physical pins on the RT1180? If they are available, could you please specify which pads/pins they correspond to and how to enable them?

Thank you very much for your assistance!

Best regards,

[Sam_Gao]

Hi 

Is this the AN that this question involves? https://www.nxp.com/docs/en/application-note/AN14155.pdf 

Reaching the OP (Operational) state confirms that EtherCAT communication is established, but it does not automatically start the PLC logic required to drive the LEDs. The issue is likely that the EtherCAT Slave Controller (ESC) variables are not linked to the PLC project variables, or the PLC is not in the "Run" state.

Q1. Enabling LED Control in TwinCAT

 In your TwinCAT project, you must explicitly link the ESC's RxPDO variable (often named LED or Output ) to the corresponding PLC input variable. Right-click the variable in the Solution Explorer and select Change Link (section. 6 Using TWINCAT3 in Run mode). Then, after linking, click Activate Configuration in the toolbar to apply the mapping. Click the Run PLC (green play button) in the TwinCAT toolbar. The EtherCAT state machine can be in OP while the PLC is stopped; the LEDs will only toggle if the PLC application is actively running

Sanity Check: To verify hardware without the PLC, switch TwinCAT to Config Mode , ensure the slave is in OP , and use the Online Write function to write 1 or 0 directly to the LED variable in the RxPDO list. If the LED toggles, the hardware is fine, and the issue is the PLC linkage/state 

Q2. LED GPIO Mapping

For the i.MX RT1180 EVK, the digital_io demo typically maps the "User LED" to the Green LED .

• GPIO Pin: GPIO_AD_27
• Pad Name: GPIO_AD_27
• Board Component: User LED (Green)

Q3. SYNC0 and SYNC1 Signal Routing

The SYNC0 and SYNC1 signals from the EtherCAT Slave Controller are not routed to external physical pins by default in the standard IOMUX configuration. These signals are designed to trigger internal interrupts (IRQ) within the i.MX RT1180 to synchronize the local application (e.g., motor control loop) with the EtherCAT Distributed Clock (DC).

You cannot measure these signals directly with an oscilloscope on the EVK headers. To evaluate timing accuracy, you must toggle a spare GPIO pin (like GPIO_AD_26 ) inside the Sync0/Sync1 interrupt service routine (ISR) and measure that GPIO pin's jitter relative to the master's cycle.

[kejin-tan]

My issue has been resolved—thank you again!

[kejin-tan · Accepted solution]

Thanks for your reply。

Yes，I have carefully followed the instructions provided in the documentation you shared https://www.nxp.com/docs/en/application-note/AN14155.pdf , and I have already configured the LED link. However, I am unable to control the LED state—even when attempting to directly write values via TwinCAT by right-clicking and using "Online Write" with either “0” or “1”.

Do I need to manually read the corresponding PDO-mapped address within the APPL_OutputMapping function in the digital_io.c file (generated by SSC for the slave device), and then explicitly set the GPIO level (e.g., GPIO_AD_27) in software based on that data to control the LED?

Additionally, regarding the MX1180 EtherCAT chip: the Reference Manual does not specify the memory map for User RAM and Process Data RAM. Are these memory regions identical to those defined in Beckhoff’s documentation—specifically:

• User RAM: 0xF80 – 0xFFF
• Process Data RAM: 0x1000 – 0xFFFF?