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As a test, do both the TXD and RXD LEDs blink when home assistant attempts to communicate, even when you have the Danfoss device disconnected or powered off? If not, the fact that both TXD and RXD are flashing means the Danfoss device is responding. Perhaps it is responding too fast and...

Yes, you would need a second USB to RS-485 adapter. But, you never cross-wire RS-485. If you have two of the same adapters, you would connect A to A and B to B. Note, however, the A and B labeling on RS-485 devices is not standardized. Some vendors use A for the RS-485 + signal and B for the...

The request packets seem to be identical, so your slave and register addressing settings match. My guess is it's either a timing issue, or perhaps your USB to RS-485 adapter is not actually the /dev/ttyUSB0 device. Try changing the following to match your Modbus Poll settings: delay: 0...

Please post screenshots of the communication settings and register definitions you're using successfully in Modbus Poll and also the communication settings and register definitions you have setup in home assistant. Also, are you sure there are no responses at all? Could the device be returning...

FTP communications will have no impact on Modbus/TCP communications. They are entirely independent Ethernet communication protocols. Multiple Ethernet communication protocols can, and do, operate simultaneously and independently of one another. Think of it like this, the computer (or...

OK, so if the end goal is to simply get the RTUs' log files onto the PC, then the MTU doesn't need to be involved at all and the current Modbus/TCP communication can be left alone. Since the PC, MTU, and RTU's are all currently on the same Ethernet network, you should be able to do FTP...

The Modbus protocol does not support file transfer. The ioLogik 2500's built-in data logger supports FTP transfers that allows you to retrieve the CSV file stored on the SD card from a PC, if that is your end goal. Alternatively, it seems that the ioLogik 2500 can log I/O data directly to an...

Not exactly. PROFIBUS is actually a bit more complicated than what I explained in my last post. I only explained the most commonly used data transfer method, which is the cyclic I/O data. However, in addition to cyclic I/O data transfer, PROFIBUS also supports acyclic data transfer in a...

As you already stated, Modbus does not have timestamps, therefore, there is no way to retrieve a time stamp (regardless of whether the connection is stable or breaks) when using Modbus. It appears the Moxa ioLogik 2500 Series supports OPC UA (Moxa calls this MX-AOPC UA)...

PROFIBUS and Modbus use very different data models and data exchange methods. Modbus is an object-based, request/response protocol. For example, the master makes a request for Holding Registers 123 - 132 and the slave responds with the values for those specific registers. PROFIBUS, on the...

In general, any device that has both an Ethernet port and an RS-485 port should allow communication on both simultaneously. It should be stated in the device's user manual if this is not the case. Therefore, you should be able to communicate Modbus/TCP via your RTAC to the meters' Ethernet...

From reviewing the manual for the inverter, and the fact that it only exposes the RS-485 + and - signals, I would suspect it is a non-isolated RS-485 device. This probably means the inverter uses it's "internal grounding terminal" as the RS-485 0V reference. Therefore, how you have grounded the...

One other thing. I know you're currently focusing on noise, but another, more common, cause of communication issues, such as the issue you're seeing, is not connecting the devices' RS-485 ground references properly. In other words, if all of the RS-485 devices do not share a common 0V ground...

The statement that RS-485 communication wires should be routed separately from input wires, output wires, power wires, etc. is a common disclaimer in documentation for devices that generate electromagnetic interference (EMI). To add to this, the worst scenario is when the RS-485 cabling is run...

RS-485 is quite robust and has excellent noise immunity, but only if you use the proper RS-485 cabling and make the proper connections. AC noise can certainly cause issues if all wiring recommendations are not properly followed. This is especially true around sources of large electrical...

I agree with David_2 that something seems to be wrong with how you're capturing the signals. I believe the "FE" shown in green indicates a Framing Error, meaning the number of bits detected does not match the expected number of bits for the current baud rate, parity, and stop bit settings. As...

You're welcome. I'm happy to help. I hope you're able to get the issue resolved with the manufacturer.

Yeah, it looks like the response for the single register request also has the last byte stuck at ff (it shows 08 ff instead of the correct CRC of 08 45). Strange that both ModScan and Modbus Poll would show timeout errors or insufficient bytes under different scenarios when it's an incorrect CRC...

I noticed it appears you're using an old version of the Optimation software, 1.3.1. The current version is 1.6.6 according to the product's web page. Perhaps the latest version of Optimation includes new firmware for the DAT11, as the manual states the software can be used for updating the...

The hardware flow control is typically for RS-232, not RS-485. There's a small chance it might do something with the CH340 chip, but that's unlikely. It's also doubtful the timing settings will make any difference. Your timeout is already more than enough at 2 seconds. You could try really...