Search results

Please stop trying to manually craft and decode Modbus packets and use a proper Modbus master simulator, such as one that I linked above. There is too much potential for error when manually encoding and decoding packets using a terminal emulator to communicate to a Modbus device. It will also be...

What specific register numbers are you requesting? For example, for the first current register, are you requesting Input Register 16 or Input Register 30016, i.e. using Function Code 04? Have you tried reading Holding Register 16 and Holding Register 30016, i.e. using Function Code 03?

Hello and welcome to the forum. The first thing I would try is using a Modbus master simulator, such as ModScan, Simply Modbus, or Modbus Poll. Start by reading a single value from the meter, such as the Voltage L1 L-N at Start Address 30000. However, keep in mind the following: This value is...

Hello and welcome to the Control.com forums. We are happy to help answer specific questions you may have about Modbus or help you resolve issues you encounter while trying to complete your project. But first, I recommend you read up on Modbus. Here are some recommended resources (I suggest...

There is such a thing as 4-wire RS-485 that uses four signal lines. And, as NetworkMan already stated, some manufacturers/suppliers that claim a device is RS-422 is really a 4-wire RS-485 device. Because RS-485's electrical specifications are within the range of RS-422's specifications, RS-485...

I suggest trying to gain more insight into the issue. It seems you've already determined that the issue probably lies in Home Assistant and not in the Fronius, since you stated that when communicating between Victron and Fronius, the writes work quickly. Therefore, focus on what Home Assitant...

I apologize in advance because this is going to sound harsh. You're a new member here and created several threads on this topic (here as well as on Stack Overflow), looking for someone to do your work for you. The engineering challenges you're facing are the "secret sauce" for protocol...

Are you actually seeing a lag (where the event is always reported, but it's reported after significant time has passed) or are you encountering missed events (where a message should have been sent but never is)? Is your PC the Modbus client (master), making read requests to retrieve the sensor...

Here are some options for capturing Modbus RTU traffic. https://www.eltima.com/modbus-sniffer.html https://ioninja.com/plugins/modbus.html https://github.com/jzhvymetal/WiresharkSerialAdapter Although it's free, there is a little bit of setup required for that last one (which is all shown in...

Of course, the flow meter can't differentiate between a computer sending Modbus packets to it versus a PLC. So what's different? Assuming the same registers are being accessed (i.e. both the computer and PLC are sending the same requests), it could come down to timing or the frequency of the...

You don't appear to be changing the state of your RE/DE output signals correctly when trying to transmit. The following lines are commented out in your send_rs485_to_device function: // gpio_set_level(RS485_ENABLE_PIN, 1); // Enable TX mode // vTaskDelay(50 / portTICK_PERIOD_MS); // Ensure...

The issue is not (only) an invalid checksum. The response bytes in your images are nonsensical garbage and not even the correct length. I think you need to take a few steps back and start at the beginning. How are you connecting your computer to the PIC16F? Are you using RS-485, RS-232, etc...

55 FF is the preamble for BACnet MS/TP packets. It seems the device you have is communicating using the BACnet MS/TP protocol, not Modbus. Perhaps the device supports both protocols and you simply need to change a configuration setting on the device for it to use Modbus instead of BACnet.

Again, there's no code in your post. Let's forget about the code for now. Please answer all of the following questions: Which device is supposed to initiate read or write requests - the ESP32 or your computer? Are you now using Modbus Slave on your computer instead of Modbus Poll? Are you...

There was no code in your post. Also, let's back up a little here. In order to communicate RS-485 between an ESP32 and a computer, you must be using a TTL to RS-485 converter with the ESP32 and a USB to RS-485 converter with the computer. Please confirm this is what you're doing. If the above...

Before answering your question, we first need to clarify the terminology. In Modbus, the device that sends requests is the client. The remote device that responds to requests is the server. Modbus does not have any generic NOP commands. However, it may be possible to resolve this issue at the...

If you're still having problems after downloading and using the Modbus Slave application instead of the Modbus Poll application, please post your complete code for your ESP32.

Modbus Poll is a Modbus master simulator. If your ESP32 is indeed a master, then this won't work, as a Modbus master cannot communicate to another Modbus master. You would need to use the Modbus slave simulator instead (https://www.modbustools.com/modbus_slave.html). If you mistyped, and you...

Hello, and welcome to the forums! In order to provide helpful recommendations, we're going to need more details. What device or equipment is generating this error? Are there additional details included with this error, perhaps found in a log file, or similar? For example, is the IP address...

The reason is because of how Ethernet switches work. It sounds like you have a PLC, the robot, and a computer running Wireshark connected to an Ethernet switch. Because TCP packets (including Modbus) are unicast messages, the Ethernet switch sends those messages only to the Ethernet port in...