ModbusTCP refuses to connect but I can see OPTA on network

Software PLC IDE
1

I feel like I'm banging my head into a wall here, I've tried two different computers and two different routers and I cant get the OPTA to connect to the PLC IDE over ModbusTCP. It might be as simple as I have the wrong setting somewhere but I've tried several different tutorials and followed them to a T, still no luck.

I can get it to upload and connect over USB no problem, but ModbusTCP will not cooperate for the life of me. I'm on the newest version of the IDE unless they launched 1.0.7 in the last couple hours, I can ping and see the OPTA on the network, I just cant get the PLC IDE to connect to it.

Does anyone have any ideas on how I might be able to get it to connect or if this is a known bug with 1.0.6?

1 Like
2

Hello, I have exactly the same issue as @jeff_the_plant and I can give some more details on this issue.

Reproduction steps:

  1. I read the MAC address of the Ethernet Port using the QR-Code on the device
  2. I added a sketch and entered the IP-Address 192.168.0.51 in my sketch
  3. Uploaded the sketch via Modbus over COM using slave id 247
  4. I have connected the OPTA to the Ethernet
  5. I tested if Modbus Slave is responding on port 502 by using PowerShell
    Powershell: tnc 192.168.0.51 -p 502 --> Result was "Ping ok", Connection "Success" --> so everything fine.
    PS C:\Program Files\PowerShell\7> tnc 192.168.0.51 -p 502
    ComputerName : 192.168.0.51
    RemoteAddress : 192.168.0.51
    RemotePort : 502
    InterfaceAlias : WLAN
    SourceAddress : 192.168.0.34
    TcpTestSucceeded : True

BUT when I try to connect to OPTA using ModbusTCP in PLC-IDE I get the same error message in bottom right corner.

The ModbusTCP Diagnostic window shows, that the ModbusTCP slave on the Opta is responding using Modbus protocol but answers with a Modbus error code:
Request from PLC-IDE: 7C 16 00 00 00 06 FF 03 FD E9 00 02
Response from Opta is: 7C 16 00 00 00 03 FF 83 02

This means in Modbus Exception codes that PLC-IDE seems to read data from address that is not allowed.

I hope this helps the PLC-IDE developer to find the bug as I am pretty sure this is just a little bug in PLC-IDE reading from the wrong address range.

3

@aroithervoigt and @jeff_the_plant The Short answer is modbusTCP supposedly works in running projects but the current software revision, 1.0.6 , does not support modbusTCP for programming and OTA updates. There is no current estimate as to when this will be updated to work so I would not rely on it for project communications at this time.

4

@incompetentoe
@jeff_the_plant

Please see the private messages I have sent you and respond.

Thank you.

5

Me having same problem...
Can't upload code over Ethernet (ModbusTCP not showed up in setup Comms tab)

6

Understood. But this reduces the value of the device a lot as it cannot be updated or programmed without physical access using USB-C port and COM-Port on a programming machine. With the Modbus-TCP programming option the value of the device would be much higher as it could be monitored and programmed over a network which is very important in IoT applications when you have many distributed devices in the field.
I really hope the Modbus-TCP programming feature will return very soon in the next release of the PLC-IDE.

2 Likes
7

Hello Perry, I would be interested if you have some information regarding this topic. Thanks in advance.

9

I've closed this topic pending a satisfactory outcome to a private discussion I'm having with the OP. If the OP wants to continue this topic I will open it at their request.

Also, please don't hijack other people's topics with your own questions, start your own topic with your own questions.