Is there some of firewall in your windows system trying to protect something?
Maybe try with an old windows 7 (or XP) system while not connected to internet.
Maybe try with an old windows 7 (or XP) system while not connected to internet.
I just wanted to provide some clarification on this.Good afternoon dear gentlemen,
Yesterday morning happened something strange to the Modbus TCP IP connection, which was successfully maintained all day long yesterday.
When I energised MC 750, and tried to re- establish Modbus TCP-IP communication, it failed to open. But some minutes afterwards with the same software the Modbus UDP-IP connection's been established. Please have a look at the picture below:
View attachment 726
Although the device ID's been set to 33(hex 21) in the communication traffic table it is changing its value from 21 to 01 and so on.
But when I deenergised the MC 750 the stings in the communications traffic table continued to run! And "No coonnection" message has not been launched by the software!
On the rear of MC 750 the leds been blinking frequently when Modbus TCP IP communication was active.
But now they blink only few seconds within it's been energised.
Are there any means(an IT softwares) to diagnose connections problems as network adaptor failure on the device, unstable connection in the cable headers, etc? To understand what possible events may lead to Modbus TCP IP connection lost?
Faithfully.
It's not a problem to use an older version of Modbus Poll, you just need to view the values in hexadecimal, which you are able to do.Begging your pardon for having use an elder version of Modbus Poll instead of the newest 9.4.4 version. It doesn't have a possibility of showing data in Hex-ASCII format, but only HEX. How much is the differnce?
Yes, this is correct.Does it mean that “03 Read Holding Registers (4x) would have a 40000 offset? Does 4x mean 40000 offset and 3x mean 30000 offset?
An Input Register is simply a read-only register, while a Holding Register is read/write. The use of each is vendor-dependent.Input registers I assume means the registers to temporarily(until MC is powered on) bearing input data(voltage, current etc. values )?
Holding registers I assume means the registers to permanently bear(in non volatile memory) the data, these are “Connection Mode”, “CT Secondary” etc, right?
The 0-based numbering versus 1-based is just a convention that Modbus uses. The register address that gets encoded into the packet is 0-based (i.e. 1 less than the 1-based register number).This I get like there is the other type of registers, not “Input Registers” and “Holding Registers” which has an offset equal to 1. So that the 1st register refers to 0.
Also the 3rd register refers to 2nd. And this is called 1-based numbering. Is this reasoning correct?
Good morning, dear sir!Great! Your calculations look correct to me. You should be able to confirm the values using the meter's display.
Your next step is to try this with your homebrewed software. You can enter one of the TX packet's shown in Modbus Poll (one that has the 21 unit ID, not the 01 unit ID) in your software and you should get a response from the meter.
Good morning, dear sir!
Yesterday afternoon and today morning I have been wondering on how can Modbus Poll manage to extract valuable data from Mc750 but my software could not.
Based on your valuable advice and reason I came up with a plan for further work on homebrewed software:
1. I've been adviced implicitly(please have a look at screnshot below) on forum not to use 'Winsock' control in my software. As VB.NET like other programming languages of .NET uses 'Namespace' paradigm, it is beside of purpose use legacy(after VB6) 'Winsock', when 'System.Net.Sockets' namespace methods are available.
2. Since Modbus Poll is enabled to extract valuable data from MC750, and my software could only get the same string input before, there is some difference in packet exchange maybe. That could be probably caught by Wireshark.
3. I captured MC750---ModbusPoll and MC750---"My software" packet exchange, and think how analyze them.
4. After having caught differences on wireshark(if happens so) let's analyze them and making some conclusions on how homebrewed software should operate.
5. Seeing the difference and making right conclusions could enable me to design the correct software probably capable of extracting valuable data from MC750-760 input registers.
Please have a look at the archive which contains wireshark logs.
Faithfully.
Good afternoon, dear sir!It appears the Wireshark captures are only of Modbus Poll, is this correct? Are you able to capture packets of your software sending transmissions to the MC 750?
As a general recommendation, I suggest you look into using an existing .NET Modbus library for your software, such as the following, for example:
http://easymodbustcp.net/en/
Sir, concerning to this link, are you advicing me to have the .NET library downloaded, to have my modbus homebrewed software worked properly?It appears the Wireshark captures are only of Modbus Poll, is this correct? Are you able to capture packets of your software sending transmissions to the MC 750?
As a general recommendation, I suggest you look into using an existing .NET Modbus library for your software, such as the following, for example:
http://easymodbustcp.net/en/
by Bob Odhiambo
by Seth Price