Communicator error “unable to read data packet header”

[OPCUser]

Hi Mikhail,

i ran into a problem today. Communicator stopped working
all of a sudden giving me the error: “Error checking server connection:
Incorrect format of data received from the server: unable to read data packet header”

Here is the communicator log:

——————————————————————————–
2024-09-05 15:47:44 [OPC-WINCC][OPCSrv][ACT] Communicator 6.2.0.0 started
2024-09-05 15:47:44 [OPC-WINCC][OPCSrv][ACT] Storage FileStorage 6.2.0.0 loaded from file C:\Program Files\SCADA\ScadaComm\FileStorage.dll
2024-09-05 15:47:44 [OPC-WINCC][OPCSrv][ACT] Start logic processing
2024-09-05 15:47:44 [OPC-WINCC][OPCSrv][ACT] Driver DrvDsOpcUaServer 6.0.0.2 loaded from file C:\Program Files\SCADA\ScadaComm\Drv\DrvDsOpcUaServer.Logic.dll
2024-09-05 15:47:44 [OPC-WINCC][OPCSrv][ACT] Driver DrvDsScadaServer 6.0.1.1 loaded from file C:\Program Files\SCADA\ScadaComm\Drv\DrvDsScadaServer.Logic.dll
2024-09-05 15:47:44 [OPC-WINCC][OPCSrv][ACT] Driver DrvOpcClassic 6.0.1.2 loaded from file C:\Program Files\SCADA\ScadaComm\Drv\DrvOpcClassic.Logic.dll
2024-09-05 15:47:44 [OPC-WINCC][OPCSrv][ACT] Data source ScadaServer initialized successfully
2024-09-05 15:47:44 [OPC-WINCC][OPCSrv][ACT] Data source OpcUaServer initialized successfully
2024-09-05 15:47:45 [OPC-WINCC][OPCSrv][ACT] Data source ScadaServer: Receive the configuration database
2024-09-05 15:47:47 [OPC-WINCC][OPCSrv][ERR] Data source ScadaServer: Error checking server connection:
Incorrect format of data received from the server: unable to read data packet header
2024-09-05 15:47:47 [OPC-WINCC][OPCSrv][ERR] Unable to start communication lines because the configuration database is not received
2024-09-05 15:47:49 [OPC-WINCC][OPCSrv][ACT] Stop communication lines
2024-09-05 15:47:49 [OPC-WINCC][OPCSrv][ACT] All communication lines are stopped
2024-09-05 15:47:49 [OPC-WINCC][OPCSrv][ACT] Logic processing is stopped
2024-09-05 15:47:49 [OPC-WINCC][OPCSrv][ACT] Communicator is stopped
——————————————————————————–

Can you point me to where the problem is?

Thanks in advance.

David

[Mikhail]

Hi,

A possible reason is that TCP port 10000 has started to be used by another application, not the Server app.

[OPCUser]

Hi there,

you were right, i had added influxDB as a datasource to grafana on the machine thats running RapidSCADA and Grafana.
I changed the port of Server and Communicator to 10003 (10001 and 10002 wasnt working for me) and then it was fine again.

Thank you,

David

[Mikhail]

Hi,

That’s good.
I suggest TCP View utility to check all ports in use.

[elee]

Hello,

I am having the same error, here are the logs:

During the Uploads:
Transfer configuration
Archive size: 157,059 bytes

Stop the Communicator service
Service control command failed
Stop the Webstation service
Service control command completed successfully
Restart the Server service
Service control command completed successfully
Start the Communicator service
Service control command failed
Start the Webstation service
Service control command completed successfully

Configuration uploaded successfully

ScadaComm.log:
——————————————————————————–
2026-06-25 14:58:42 [webserver][root][ACT] Communicator 6.2.0.1 started
2026-06-25 14:58:42 [webserver][root][ACT] Storage FileStorage 6.4.0.0 loaded from file /opt/scada/ScadaComm/FileStorage.dll
2026-06-25 14:58:42 [webserver][root][ACT] Start logic processing
2026-06-25 14:58:42 [webserver][root][ACT] Driver DrvCnlBasic 6.1.0.1 loaded from file /opt/scada/ScadaComm/Drv/DrvCnlBasic.Logic.dll
2026-06-25 14:58:42 [webserver][root][ACT] Driver DrvDsScadaServer 6.0.1.1 loaded from file /opt/scada/ScadaComm/Drv/DrvDsScadaServer.Logic.dll
2026-06-25 14:58:42 [webserver][root][ACT] Driver DrvModbus 6.0.0.5 loaded from file /opt/scada/ScadaComm/Drv/DrvModbus.Logic.dll
2026-06-25 14:58:42 [webserver][root][ACT] Driver DrvSnmp 6.0.0.1 loaded from file /opt/scada/ScadaComm/Drv/DrvSnmp.Logic.dll
2026-06-25 14:58:42 [webserver][root][ACT] Data source ScadaServer initialized successfully
2026-06-25 14:58:42 [webserver][root][ACT] Data source ScadaServer: Receive the configuration database
2026-06-25 14:58:42 [webserver][root][ACT] Data source ScadaServer: The configuration database has been received successfully
2026-06-25 14:58:42 [webserver][root][ACT] Start communication lines
2026-06-25 14:58:42 [webserver][root][ACT] Start reading commands from files
2026-06-25 14:58:42 [webserver][root][ACT] Data source ScadaServer: Connection state is Logged In
2026-06-25 15:00:00 [webserver][root][ACT] Stop communication lines
2026-06-25 15:00:09 [webserver][root][ERR] Data source ScadaServer: Error receiving telecontrol commands:
Incorrect format of data received from the server: unable to read data packet header
2026-06-25 15:00:09 [webserver][root][ACT] Data source ScadaServer: Connection state is Error
2026-06-25 15:00:09 [webserver][root][ERR] Data source ScadaServer: Error receiving telecontrol commands:
Unable to write data to the transport connection: Broken pipe.
2026-06-25 15:00:09 [webserver][root][ERR] Data source ScadaServer: Error receiving telecontrol commands:
Connection refused [::ffff:10.1.10.141]:10000
2026-06-25 15:00:09 [webserver][root][ACT] Unable to stop logic processing for a specified time
2026-06-25 15:00:09 [webserver][root][ACT] Communicator is stopped
——————————————————————————–
2026-06-25 15:00:10 [webserver][root][WARN] Following communication lines are still working: 2
——————————————————————————–
2026-06-25 15:00:52 [webserver][root][ACT] Communicator 6.2.0.1 started
2026-06-25 15:00:52 [webserver][root][ACT] Storage FileStorage 6.4.0.0 loaded from file /opt/scada/ScadaComm/FileStorage.dll
2026-06-25 15:00:52 [webserver][root][ACT] Start logic processing
2026-06-25 15:00:52 [webserver][root][ACT] Driver DrvCnlBasic 6.1.0.1 loaded from file /opt/scada/ScadaComm/Drv/DrvCnlBasic.Logic.dll
2026-06-25 15:00:52 [webserver][root][ACT] Driver DrvDsScadaServer 6.0.1.1 loaded from file /opt/scada/ScadaComm/Drv/DrvDsScadaServer.Logic.dll
2026-06-25 15:00:52 [webserver][root][ACT] Driver DrvModbus 6.0.0.5 loaded from file /opt/scada/ScadaComm/Drv/DrvModbus.Logic.dll
2026-06-25 15:00:52 [webserver][root][ACT] Driver DrvSnmp 6.0.0.1 loaded from file /opt/scada/ScadaComm/Drv/DrvSnmp.Logic.dll
2026-06-25 15:00:52 [webserver][root][ACT] Data source ScadaServer initialized successfully
2026-06-25 15:00:52 [webserver][root][ACT] Data source ScadaServer: Receive the configuration database
2026-06-25 15:00:52 [webserver][root][ACT] Data source ScadaServer: The configuration database has been received successfully
2026-06-25 15:00:52 [webserver][root][ACT] Start communication lines
2026-06-25 15:00:53 [webserver][root][ACT] Start reading commands from files
2026-06-25 15:00:53 [webserver][root][ACT] Data source ScadaServer: Connection state is Logged In

When searching for active ports on the server sudo ss -tulpn
it only shows dotnet as using 10000/8/2
When searching for 10000, sudo ss -tulpn | grep 10000
it shows dotnet but the port is in red…

Thank you for your help!

[elee]

Edit: this issue is intermittent when uploading configurations

[Mikhail]

> Stop the Communicator service
> Service control command failed
The above messages indicate that Communicator is taking too long to stop.

> 2026-06-25 15:00:10 [webserver][root][WARN] Following communication lines are still working: 2
This one similar.

What does line #2 do?
It should be optimized.

[elee]

Line 2 has TCP connection timeout errors, how can I optimize this line? There are 4 snmp devices. I can move one to modbus (line 1), as that device has both options, the others do not. What is the maximum number of devices per line?

Is it fair to assume that each communication line should have all devices of that driver type assigned?

Line 2 Main Options: (program defaults)
request retries on error – 3
delay after polling cycle – 0
TCP Client, reconnectAfter = 5

Line 2 Custom Options:
TansMode = TCP

Line 2 Device Polling: (program defaults)
Timeout = 1000
Delay = 200
Time = 0
Period = 0
Command Line = (blank)

[Author]

Posts