PM5560 Gateway Instability with PM800 Meters

[Veronika.Salinas]

Hello everyone,

I’m working with a client who originally had 10 PM800 meters connected via an EBX510 gateway. After a lightning storm, several PM800 meters and the EBX510’s RS-485 input were damaged. Some of the meters were replaced with PM5560 units, and the remaining PM800 meters were connected to a PM5560 acting as a gateway.

Although the setup worked briefly, the communication quickly became unstable, with frequent and sudden disconnections. The original RS-485 wiring was not replaced.

I experienced a very similar case a few years ago with 12 PM800 meters and an EBX510. In that case, using a PM5560 as a gateway also led to unstable communication, which was resolved only after replacing it with a PAS800 gateway.

Has anyone encountered limitations or instability when using the PM5560 as a gateway for PM800 devices?

Thanks in advance for your input!

[Mehran_Mehrnia]

Hi @Veronika.Salinas 

There is one old FAQ addressing the similar behavior when PM5560 is configured as a Gateway:

When using the PM5560 as a Modbus gateway there may be excessive timeouts for downstream devices.

However, you have not mentioned the firmware version of the PM5560 meter. Since many modifications and improvements have been made to the firmware, it is recommended to use the latest version.

Also, how does the Modbus client poll the slave devices, for example, how many registers are read per packet, or is it using scattered reads? How frequently does the client read data from the devices?

As a starting point, please ensure the physical wiring and integrity of the RS485 daisy-chain bus, including the bus length, correct serial settings on both the gateway and slave devices, timeout configurations, and other relevant parameters.

PM5500 User guide, Configuring serial settings:

For test, minimize the number of slave devices and the bus length (if it is too long), use a 100-ohm termination resistor, and follow the recommendations provided in the knowledge base article above and the installation guide.

PM5560 Installation Guide:

Best regards,

-Mehran

L3 Expert Advanced metering

[Veronika.Salinas]

Hello @Mehran_Mehrnia 

I wanted to let you know that I've followed the recommended steps. First, I attempted to change the baud rate, but this did not yield positive results. Then, I installed a 100-ohm termination resistor at the end of the RS-485 daisy chain (on the last meter), but the issue remained unresolved.

After that, I proceeded to update the firmware of the meter configured as a gateway. It was running an outdated version (v2.5.3), so I upgraded it to version 4.2.1. Unfortunately, the problem persists even after the update.

At the moment, I don't have access to an RS-485 to USB converter, so I can't test the communication with the PM800 meters directly.

Do you know of any additional actions or alternatives I could try to help resolve this issue?

Thank you very much for your support.

Best regards,

Veronika

[Mehran_Mehrnia · Accepted solution]

Hi @Veronika.Salinas 

You're welcome.

If you can bypass the gateway using a functional RS-485 to USB converter, it will help isolate the root cause, which could either be the gateway (PM5560) or the slave device (PM800).

Also, as mentioned earlier, please ensure that the PM5560 is configured correctly as a gateway, according to the settings highlighted in the table.

If the issue persists, please contact your local tech support for more assistance.

Best Regards,

-Mehran

L3 Expert Advanced metering