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Can you provide more context and details on what it is you're trying to do? You mention "serial port read function" and "readexisting", but don't tell us what programming language or library these functions come from? For example, are you using C# with .NET? .NET has a SerialPort.ReadExisting...

Can you clarify what you mean by "the response is read"? Does this mean that your program correctly receives the response? In the table you attached, there does not seem to be a difference between the two transactions shown in lines 4289 - 4293 and lines 4301 - 4305. You stated that line 4302...

The Modbus specification defines that the end of a Modbus RTU message is marked by a silent interval of at least 3.5 character times. My guess is that your Modbus RTU Master code is not using this 3.5 character time to detect that a full packet was received, but rather simply polling the...

Your requests are valid Modbus requests, which is also confirmed based on the fact that the PLC is responding at all. However, either the PLC is not correctly sending its responses (which likely isn't the case because Simply Modbus can communicate successfully with the PLC) or your packet...

I'm sorry, but I can't make sense of the data you're showing for the requests and responses. Please show the full requests and responses (including slave address, function code, address, number of points, and CRC fields) and either separate the decimal numbers using a space or write them in...

With the very limited information you provided, it is not possible for anyone to help you. Please reply with the exact data bytes that your Modbus RTU Master is sending and the data bytes that the PLC is responding with. I also recommend that you try communicating to the PLC using third-party...

There should not be any issues with having the master in the middle of the daisy chain. Just confirm that any biasing or termination dipswitches/settings on the master are disabled. If you think about it, this question could equally apply to Modbus RTU slaves, because like masters, slaves both...

There are several Modbus simulator packages available. WinTECH has both a master and slave called ModScan and ModSim: http://win-tech.com/ Simply Modbus also makes both master and slave simulators: http://www.simplymodbus.ca/ Witte Software also has both, with Modbus Poll and Modbus Slave...

Because the client is the device that initiates the TCP connection, I don't believe the server needs to be able to ping the client. Just think about how you access web sites from a PC to the internet. Your computer can ping the web site, but the server hosting the web site cannot ping your...

Are you trying to solve a communication problem on your Modbus RTU network that you believe is caused by overloading the bus (i.e. having 130 devices on one RS-485 bus)? The limitation of RS-485 is actually defined as 32 "Unit Loads". For older RS-485 devices, it may be true that 1 device...

ICC has gateways that can be configured for Modbus to Modbus conversion and can remap 4X registers to 3X registers. For Modbus RTU, I recommend our Mirius gateway http://www.iccdesigns.com/protocol-gateways/66-mirius.html For Modbus/TCP, I recommend our ETH-1000 gateway...

The only Modbus manual I could find is the 4 page datasheet for the Modbus Power Control license, which I linked to in my last post. That document lists the communication parameters, register format, and register list.

Is your device licensed for Modbus? According to the blue'Log XM / XC page on the Meteocontrol website, the "Power Control Modbus" functionality is a separate license...

Another solution would be to use a gateway between your PLC and the new inverter. The gateway would be configured to emulate the old inverter and present the same registers/coils to the PLC. The gateway would translate the registers/coils to the appropriate registers/coils for the new inverter...

I assume by front panel display, you're referring to the S7999D SOLA Operator Interface Display. If so, I believe you can keep this connected, as the display is designed to have a BAS connected to one its RS-485 ports and 1 or more SOLA controllers to the other RS-485 port. You should be able to...

The default password is "sola", however this can be changed on the SOLA controller, so confirm that you are sending the correct password as configured on your controller. Also, this password must be sent at least every 10 minutes, as the SOLA automatically logs you out every 10 minutes. You can...

We've successfully interfaced our gateway products to several boilers that use the Honeywell SOLA controller. I believe you may need to write the entire password field (10 registers total) starting at Holding Register 178 (40178 - 40187). You may also want to try writing to the other password...

If you are looking for a tool that will read the values of the Modbus registers on your controller and verify them against predetermined values, this can be done with our free ICC Modbus Master Tool software available here: http://www.iccdesigns.com/software/43-icc-modbus-master-tool.html To...

You could use the ICC ETH-1000 gateway and configure its RS-485 port for Modbus RTU Sniffer and its Ethernet port for Modbus/TCP Server. This will have the least impact on your existing Modbus RTU bus. The Modbus RTU Sniffer driver passively listens to the existing requests and responses on...

Either of the libraries that the OP mentioned will work for the entire 65K address space. The NModbus library takes a ushort argument for the start address when reading/writing registers. Therefore, it supports values from 0 - 65,535, which is the entire range. The EasyModbus library takes...