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Thank you for the Modbus Poll settings. Please provide screenshots of the settings used in the Schneider Power Monitoring Expert software.

Does the software show a reason it's not communicating, such as an error message or error code? Please also post the settings you've configured in Modbus Poll to establish successful communications and the current settings you are trying to use in Schneider Power Monitoring Expert.

Ok, that might actually be a good thing. The RXD LED should only flash when the MCB is transmitting a response. Previously, the RXD LED was on all the time, even when the MCB was not sending a response (you saw the same results with reversed polarity and regardless of what device address was...

Much clearer picture. R110 is definitely a termination resistor (it shows 121 on it). I recommend trying removing the jumper on S3 entirely (it likely connects R110 to the A1 and B1 lines) and move your wires to A1 and B1. Again, remember to try swapping the wires if one polarity doesn't work...

It's very hard to see, but perhaps R21 is a termination resistor. What numbers are printed on it? If it's 121, and it seems like traces connect it to the terminal block and the S3 jumper posts, then this would strongly indicate it is a termination resistor and S3 enables and disables the...

There appears to be a jumper on the MCB next to the green terminal block. I believe the manual calls it S3 in the wiring diagram, but does not seem to make any mention of its purpose. Is there any labeling near this jumper? It's possible this jumper enables or disables termination on the MCB.

Do you have an ohm meter (multimeter)? It's possible the MCB also has a termination resistor enabled or permanently installed. You could confirm this by powering the device off, disconnecting the wires from the A and B terminals, and measuring the resistance between A and B. If it measures near...

If swapping the polarity of the A and B lines results in the same behavior, that seems to imply that the termination resistor is essentially shorting the bus, resulting in an invalid idle voltage of less than 200mV between the A and B signals. Under this invalid state, the converter sees this as...

And what difference, if any, is there in the RXD LED and the Communication Traffic window if you swap your A and B connections on one end?

What does Modbus Poll's Communication Traffic window show? You can open this by clicking on the "Display" in the top menu and clicking "Communication...". Does the RXD LED on the converter turn off completely, or does it always stay on?

Another suggestion. When using Modbus Poll, you can view the Modbus packets exchanged between Modbus Poll and the Modbus slave device by clicking on the "Display" menu and selecting "Communication...". This will open the Communication Traffic window and show the data sent and received by Modbus...

The termination resistor is on the underside of the board, as shown on the Waveshare page I linked in my last reply. It is the small black rectangle near the green terminal block with "121" printed on it in white.

I think I found your converted and this page confirms it does have a built in 120 ohm termination resistor, which very well could be the cause of your issue. https://www.waveshare.com/usb-to-rs485.htm You could desolder that 120 ohm resistor(or otherwise disconnect it, such as by...

It might be an issue with your USB to RS-485 converter. Do you have anything else connected to the RS-485 wiring, such as termination resistors? Perhaps the USB to RS-485 has a pre-installed termination resistor (I've seen this on some cheap converters). What is the specific converter you're...

According to the manual you attached, the wallpad should be connected to the TTL1 connector on the MCB, which you appear to already have. But your USB to RS-485 adapter should be connected to the green terminal block terminals (BMS connection port) on the MCB, not to the wallpad (the manual you...

Welcome to the forum! Here are some basic Modbus troubleshooting suggestions. Modbus RTU can only have one master connected to the bus. If you are trying to connect your computer using a USB to RS-485 adapter to an existing Modbus RTU network (consisting of the white display and green control...

Many Modbus devices have a communication timeout feature that is controlled by settings for the timeout time and a timeout action. That sounds like what this Bus FailState error is. Look through the device's communication settings for settings related to this FailState feature. If you need...

I'm not familiar specifically with that energy meter, but I can provide general Modbus advice. Typically, complete lack of communication (i.e. the master's requests are timing out), is caused by either a wiring issue or a communication setting issue. Although, there are more rare causes, such...

Maybe, but you asked for the best gateway.:D In the interest of full disclosure, I am one of the product specialists at ICC for the ETH-1000 and one of the engineers that designed it.

Yes, you can use ICC's ETH-1000 to do this. Details and pricing can be found on its product page here: https://www.iccdesigns.com/millennium-series/10-eth-1000.html You would configure the Ethernet port as a Modbus/TCP Server and configure the RS-485 port as a Modbus RTU Slave. Configuration...