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Welcome to the Control.com forums! In order to better assist you with your issue, please provide more specific details of what it is you're trying to accomplish. Can you elaborate on what "clp" is? What system? What equipment is involved besides the HMI? What is the exact model number of...

Assuming the communication protocol is half duplex (which most protocols are), you could use an RS-232 tap device, such as this: https://www.digikey.com/en/products/detail/advantech-corporation/BB-9PCDT/4759754 Alternatively, you could use an RJ-11 Y splitter and make your own RS-232 tap using...

If your software is packing multiple Modbus messages into a single TCP frame, then your software must be corrected so that it sends only one Modbus message per TCP frame. You don't need to (and as you stated, nor can you) make TCP work differently. You need only modify the payload of the TCP...

You need to change your software implementation such that only a single Modbus message is contained in each TCP frame. The Modbus/TCP specification (https://modbus.org/docs/Modbus_Messaging_Implementation_Guide_V1_0b.pdf) states the following on the bottom of page 10: A TCP frame must...

I recommend consulting the Modbus specifications for the correct syntax. Refer to section 3.1.2 in the follow specification for details on the contents of a Modbus/TCP packet (i.e. MBAP Header, Function Code, Data): https://modbus.org/docs/Modbus_Messaging_Implementation_Guide_V1_0b.pdf Refer...

What write function code are you using, 6 (Write Single Register) or 16 (Write Multiple Register)? Which register(s) are you writing to? Are they 32-bit registers? From the manual you attached: Perhaps this is the cause?

Thanks for confirming. Here's the next steps that I would try. Modbus RTU Communication Confirmation Download a Modbus slave simulator software tool that supports both Modbus RTU and Modbus/TCP, such as one of the following WinTECH - ModSim Witte Software - Modbus Slave Connect your USB to...

Can you elaborate on how you determined this? For example, is the master device sending read or write requests to address 30 and there are no responses? Again, please elaborate on what this means. There can only be one master on a Modbus RTU bus and masters are the only devices that can send...

Yes, you can either: 1. (Preferred Method) Connect the USB to RS-485 converter to one end of the RS-485 bus, by daisy-chaining new wires from the first or last device to the converter. [Converter]------[First Device]------[Middle Device(s)]------[Last Device] [First Device]------[Middle...

No, unfortunately Wireshark cannot capture serial traffic. https://osqa-ask.wireshark.org/questions/23243/how-do-you-capture-serial-com-communications/ https://ask.wireshark.org/question/28935/can-wireshark-capture-serial-port-data/

Your setup with the Vlinx would only work if there is not already an existing device on the Modbus RTU bus using address 30. Since you don't have access to the equipment to know what requests are being sent, and what slave addresses are actually present, on the Modbus network, you may want to...

So you have an existing Modbus RTU network consisting of 7 Siemens PLC's and either one of those is the master or you have an 8th PLC that is the master on the network. You want to integrate these Modbus devices into your BMS via Modbus/TCP. Is this understanding correct? Is this for monitoring...

Exactly right. Unbiased, undriven RS-485 lines will be nearly the same, or exactly the same, especially when a termination resistor is connected between them. However, this violates the RS-485 specification, as it requires the differential voltage between the + and - signals to always be more...

Guessing you're using this library https://github.com/craftmetrics/esp32-modbusmaster/tree/master/src If so, a return code of 227 decimal (E3 hexadecimal) is defined as follows static const uint8_t ku8MBInvalidCRC = 0xE3; So you're getting an invalid CRC. This may be due to...

RS-485 communication issues are typically due to either incorrect wiring or incompatible communication settings. Double-check your wiring. Make sure you are connecting 3 wires: +, -, and signal reference (i.e. ground, common, etc.). Also, if either of the equipment use "A" and "B" labeling for...

Just to add further confirmation, Function Code 15 packets should only include the minimum number of bytes that hold the coils being written. If the master implementation you're using does not follow this, then it does not follow the spec and this therefore is a bug.

Welcome to the forum! Please note that it's better to start a new thread to ask your question than to resurrect a decade old thread that is only slightly related to your question. But to answer your question, there are a few options to convert between RS-485 Modbus (presumably Modbus RTU) and...

A properly implemented Modbus slave should always respond to valid requests (i.e. no CRC errors) addressed to its slave ID, even if it is an exception response stating that the requested function or register number is not supported. However, it seems this device simply does not respond at all...

For serial-based Modbus (e.g. Modbus RTU or Modbus ASCII), there can only be one master on the RS-485 bus. However, for Ethernet-based Modbus, you can actually have multiple clients (i.e. masters) communicate to a single server (i.e. slave). The number of simultaneous clients allowed depends on...

From your list, it seems to me that there are really only 2 registers with non-zero values: 32 and 86. The device may simply be masking/ignoring the upper 8 bits of the address (the "alias" registers are all multiples of 256 above those two registers). Since register 86 seems to be randomly...