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After taking another look at the original values you listed when reading the double value, FCF4D4823FF70001 Hex and 1.489383 decimal, I noticed something that may help you decode the value. A double value of 1.489383 in decimal corresponds with a hex representation of 3FF7 D482 FCF4 XXXX, after...

The Modbus mapping you attached shows that the flow meter's parameters are exposed three different ways, as doubles, floats, and signed long integers. For example, the Flow Rate can be accesses as a double by reading register addresses 105 - 108 (4 registers in total), as a float by reading...

You need to confirm the format of the value from your sensor. A double is a 64-bit encoded value, which is very rare for Modbus devices. Are you sure you don't have a 32-bit floating point value? Taking the least-significant 32-bits from your hex data, 3FF70001, and converting to decimal...

I assume that the bridge device is some sort of Modbus/TCP to Modbus RTU router or gateway, is this correct? I can't speak to the timeout error you're seeing in Intouch, but the exception response you're seeing is exception 11, which is Gateway Target Device Failed to Respond, defined by the...

One other option I just thought of, in the Modbus TCP Protocol document you attached, the "Datalogger" is described as a "Wi-Fi, 3G and 4G dongle" and it seems it's this datalogger that supports Modbus/TCP. So the other option would be to obtain a Wi-Fi DataLogger, which would presumably allow...

OK, I tracked down the issue. The manufacturer implemented Modbus RTU wrong. The CRC bytes are in the wrong order. So of course this will only work between their own products. The inverter is a Modbus RTU slave and uses slave address 17. The software is a Modbus Master and sends the following...

The diagram you drew seems to indicate that you have 8 separate Modbus RTU networks, each with its own master. Therefore, the 8 RS-485 networks could not be joined together, otherwise communications would not work as you would have multiple masters on the same bus. Did I misunderstand what you...

As you probably saw on its product page, the Mirius is approximately 90mm x 35mm x 30mm, and is about as compact as it gets. The enclosure has an integrated DIN rail clip, so perhaps you could utilize a DIN rail? Is there a specific reason why you need to mount the Mirius inside this very old...

The only device I know of on the market that can have 8 RS-485 ports and supports Ethernet is Red Lion's new Flex Edge DA70A, but you also need it with 3 RS-485 communication sleds added. I believe Red Lion has a Modbus RTU Monitor driver that may support the sniffing functionality you need...

You are correct that you would need 8 Mirius gateways to sniff your 8 Modbus RTU networks. You show an additional "gateway RTU/TCP" on your diagram, that may not be necessary. If your "Server" supports Modbus RTU, BACnet MS/TP, or any other protocol supported by the Mirius, then your server can...

Assuming this is a request for a permanent solution to supervise an existing Modbus RTU network from another device/network, ICC's Mirius gateway supports a Modbus RTU Sniffer driver, specifically designed for this purpose. The Mirius has 2 RS-485 ports. You would configure the Modbus RTU...

You've stated that you encounter this issue both when you disconnect the Modbus connector from the VFD and when you power off the VFD. One test you can try that should help you determine whether the issue is electrical or logical is to temporarily change the Modbus slave address of the VFD to...

Typically the Modbus documentation is you would need in order to establish successful Modbus communications to a device. However, sometimes these documents do require a bit of deciphering by someone experienced in Modbus. Perhaps if you would attach the above-referenced documentation and...

Checking the "PLC Addresses (Base 1)" changes how Modbus Poll interprets the Address field. Therefore, in your Read/Write Definition you must do one of the following: Set the Address to 1 and leave the "PLC Addresses (Base 1)" option unchecked Set the Address to 2 and check the "PLC Addresses...

From the document you attached under the Modbus RTU section, "Modbus addressing is offset 1 byte from the memory map. For instance the average rate, Bytes 1-4 correspond to Modbus Registers 40002 and 40003. Total information is in Bytes 21-24, or Modbus Registers 40012 and 40013." I can't say...

Some Modbus slaves implement a timeout, or fail-safe, feature whereby the slave monitors communications from the master. The slave starts a supervisory timer once it has received a Modbus request from a master. If the supervisory timer expires before a new request is received, a timeout event...

If the slaves are indeed operating the way you've described, this is a serious design flaw in the slave and should be fixed by the vendor. Have you confirmed that each slave can successfully communicate with the master when no other slave is connected? One workaround you may be able to do is...

SerialPort _serialPort = new SerialPort("COM1", 4800, Parity.Even, 8, StopBits.One); byte[] vals = {0x01, 0x01, 0x00, 0x00, 0x00, 0x08, 0x3d, 0xcc}; byte[] recv_vals; int recv_bytes; int temp_int; bool packet_received = false; _serialPort.Open(); _serialPort.Write(vals,0, vals.Length)...

No, it is not possible to receive two consecutive responses from a slave after sending a single request. Modbus uses exactly one response for every request (or no response if the targetted slave does not exist). You need to set a proper ReadTimeout time for your calls to ReadByte. After you...

Thank you for clarifying. The ReadExisting function is meant to read ASCII characters, as Modbus RTU uses binary characters, you cannot use ReadExisting. The reason for the behavior you're seeing is because the SerialPort class's Encoding property is set to ASCIIEncoding by default, which is a...