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M
Midhul_Pk
Associate III
December 16, 2025
Question

X-NUCLEO-PLM01A1: ST7580 TX/RX not continuous, no data reception, TX_ON/RX_ON LEDs not blinking

  • December 16, 2025
  • 2 replies
  • 1478 views

Hello,

I am working with two X-NUCLEO-PLM01A1 PLC expansion boards, each connected to a different STM32 MCU board.

Hardware setup:

  • Transmitter MCU: STM32C092CBT6

  • Receiver MCU: STM32G070CBT6

  • PLC modem: ST7580 on both X-NUCLEO-PLM01A1 boards

  • Both boards are connected over the same power line

Problem description:

  • I am trying both DL mode and physical data transmission.

  • Data transmission is not continuous.

  • The receiver board does not receive correct data (data is corrupted or not received).

  • The TX_ON and RX_ON LEDs on both X-NUCLEO-PLM01A1 boards remain LOW and do not blink during transmission or reception.

  • The ST7580 IC replies on SPI/UART, but no proper PLC data transfer occurs.

Additional observation:

  • I also tried using the ST-provided API / middleware available on the ST website, but the transmission gets stuck with a transmission error and does not complete successfully.

Observations:

  • SPI/UART communication between MCU and ST7580 is working.

  • T_REQ behavior has been checked.

  • Despite transmission attempts, TX_ON and RX_ON LEDs never indicate activity.

Questions:

  1. What are the possible reasons for TX_ON and RX_ON LEDs staying LOW?

  2. Are there any mandatory ST7580 configuration registers that must be set for continuous transmission?

  3. Are there known issues or differences when using different MCU families (STM32C0 vs STM32G0) with X-NUCLEO-PLM01A1?

  4. Is there any recommended initialization or timing sequence required before starting DL or physical data transmission?

  5. Could this be related to line coupling, impedance, or hardware configuration on the X-NUCLEO-PLM01A1?

  6. Are there any known limitations or required adaptations when using the ST7580 API on non-reference MCU boards?

Any guidance, reference designs, or example configurations would be very helpful.

Thank you in advance.

 

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2 replies

M
Midhul_PkAuthor
Associate III
December 15, 2025

Merged threads for the same subject.

Hello,

I am working with two X-NUCLEO-PLM01A1 PLC expansion boards, each connected to a different STM32 MCU board.

Hardware setup:

  • Transmitter MCU: STM32C092CBT6

  • Receiver MCU: STM32G070CBT6

  • PLC modem: ST7580 on both X-NUCLEO-PLM01A1 boards

  • Both boards are connected over the same power line

Problem description:

  • I am trying both DL mode and physical data transmission.

  • Data transmission is not continuous.

  • The receiver board does not receive correct data (data is corrupted or not received).

  • The TX_ON and RX_ON LEDs on both X-NUCLEO-PLM01A1 boards remain LOW and do not blink during transmission or reception.

  • The ST7580 IC replies on SPI/UART, but no proper PLC data transfer occurs.

Additional observation:

  • I also tried using the ST-provided API / middleware available on the ST website, but the transmission gets stuck with a transmission error and does not complete successfully.

Observations:

  • SPI/UART communication between MCU and ST7580 is working.

  • T_REQ behavior has been checked.

  • Despite transmission attempts, TX_ON and RX_ON LEDs never indicate activity.

Questions:

  1. What are the possible reasons for TX_ON and RX_ON LEDs staying LOW?

  2. Are there any mandatory ST7580 configuration registers that must be set for continuous transmission?

  3. Are there known issues or differences when using different MCU families (STM32C0 vs STM32G0) with X-NUCLEO-PLM01A1?

  4. Is there any recommended initialization or timing sequence required before starting DL or physical data transmission?

  5. Could this be related to line coupling, impedance, or hardware configuration on the X-NUCLEO-PLM01A1?

  6. Are there any known limitations or required adaptations when using the ST7580 API on non-reference MCU boards?

Any guidance, reference designs, or example configurations would be very helpful.

Thank you in advance.

Andrew Neil
Andrew Neil
Super User
December 15, 2025

It's not clear what "UART communication" you're talking about here?

Is it:

  • between the two STM32 boards? 
  • between the STM32 boards and something else? 
  • Over the PLC link?

 

A diagram would provide a much clearer description...

 

PS:

Also, what boards are your STM32s on, etc?

 

How to write your question to maximize your chances to find a solution

A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
M
Midhul_PkAuthor
Associate III
December 15, 2025

Let me clarify the issue more precisely.

I am using two identical setups, each consisting of:

  • One STM32 board

  • One X-NUCLEO-PLM01A1 (ST7580 PLC modem)

  • On the transmitting side, UART communication between the STM32 and the ST7580 works initially, but data transmission is not continuous. After some packets, transmission stops.

  • On the receiving side, the STM32 does not receive any data at all from its local ST7580 modem.

TDK
TDK
December 16, 2025

This is a duplicate of your previous question:

STM32C092 + X-NUCLEO-PLM01A1: UART TX works interm... - STMicroelectronics Community

 

Please don't repost the same question. You got engagement there, perhaps follow up to add more relevant details.

"If you feel a post has answered your question, please click ""Accept as Solution""."
M
Midhul_PkAuthor
Associate III
December 18, 2025

Merged threads for the same subject.

Hello st Community,

I would like to ask for your support regarding an issue I am facing with the ST7580 power line communication IC.

I am using two STM32 boards:

STM32C092CBT6 (Board 1)

STM32G072CBT6 (Board 2)

Both boards are configured with the same ST7580 configuration settings. All configuration commands are acknowledged correctly, and I receive both ACK and Confirm messages for each configuration step.

For data communication:

I am using the DL method to send data

I am transmitting 10 bytes of data

The transmitter receives the ACK and Confirm successfully

However, on the reception board, the received data is not appearing on the RX_IN power line interface. No data is observed even though:

Both boards share the same power line and common ground

Power line and hardware connections are verified and appear correct

Configuration ACK and Confirm responses are received correctly

RX_ON / TX_ON behavior:

Both RX_ON and TX_ON signals remain at logic low

Even when these pins are pulled up by the MCU, they still remain low

As a result, the corresponding RX/TX status LEDs never turn ON

Additional observation (Sniffer indication):

Occasionally, the reception board receives sniffer indication packets

However, this occurs only intermittently

In the transmit case, since ACK and Confirm are received consistently, I am unsure why the reception board sometimes reports sniffer indications instead of normal RX data

I would like to understand under what conditions the ST7580 generates sniffer indication packets and why this might happen when DL transmission appears successful

Based on this, my concerns are:

Why the reception board is not forwarding or outputting the received data on RX_IN, despite successful configuration and DL transmission acknowledgment

Whether an additional command or request is required for the reception board to output received data

Whether the constant low state of RX_ON and TX_ON indicates a configuration, pin-mux, or hardware-related issue

Why sniffer indication packets are received intermittently on the RX board even though the TX board receives ACK and Confirm messages

Could you please advise if there are any required initialization steps, operating modes, or known conditions that could cause this behavior?

Any guidance or recommendations would be greatly appreciated.

Thank you for your time and support.

Best regards,
Midhul Pk

Andrew Neil
Andrew Neil
Super User
December 18, 2025

This looks like a duplicate of your previous thread:

https://community.st.com/t5/stm32-mcus-products/x-nucleo-plm01a1-st7580-tx-rx-not-continuous-no-data-reception/td-p/864874

where you've already been asked not to duplicate threads.

 

A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
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