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+--- Thread: Modbus write error (/showthread.php?tid=5883)
Modbus write error - didac - 11.02.2025
Hello,
I have a problem. I updated genohm-scada-modbus package version 20230404 to 20240621 and FW version 20230607 to 20240426. Now I run a write command and I get this error: "Write failed: Illegal data value". The only change in Modbus profile is to add write_delay:1 in the file header. I also tried package 20231213 and I have the same error. The error doesn't always occur, ometimes write correctly. It is possible to know which mapping element triggers the error?
Code:
{
"manufacturer": "TEST",
"description": "Modbus",
"timeout": 5,
"read_swap": "n",
"write_delay":1,
"mapping": [
{"name": "Allow Heating_[R/W]",
"bus_datatype": "bool",
"type": "register",
"datatype": "uint16",
"address": 47371,
"writable": 1,
"write_multiple": 1,
"read_count": 1,
"value_delta": 1,
"value_multiplier": 1,
"value_custom": {
"0": "Off",
"1": "On"
}
},
{"name": "Allow Cooling_[R/W]",
"bus_datatype": "bool",
"type": "register",
"datatype": "uint16",
"address": 47372,
"writable": 1,
"write_multiple": 1,
"read_count": 1,
"value_delta": 1,
"value_multiplier": 1,
"value_custom": {
"0": "Off",
"1": "On"
}
}
]}RE: Modbus write error - Daniel - 11.02.2025
Use this
https://forum.logicmachine.net/showthread.php?tid=5473&pid=35418#pid35418
PS. You don't need read_count
RE: Modbus write error - didac - 11.02.2025
(11.02.2025, 11:46)Daniel Wrote: Use this
https://forum.logicmachine.net/showthread.php?tid=5473&pid=35418#pid35418
PS. You don't need read_count
i'm using this version of package
RE: Modbus write error - admin - 11.02.2025
Most likely the problem is on the physical communication level. Do you have GND connected between LM and Modbus device?
RE: Modbus write error - didac - 11.02.2025
What does this error mean? Can I know which profile item triggers it? We haven't changed anything physically, we just updated the firmware and package. It was working correctly before.
RE: Modbus write error - Daniel - 11.02.2025
If it worked, why did you need write_delay?
RE: Modbus write error - didac - 11.02.2025
Because sometimes we got a timeout error. But not this illegal value error.
RE: Modbus write error - admin - 12.02.2025
Random timeouts usually mean that the end device does not always receive the message correctly. Do you have GND connected between LM and Modbus device?
RE: Modbus write error - didac - 12.02.2025
The error only occurs when I send the same value that the parameter currently has. If the value is different i don't have the error. I will check the physical device.
Thanks!
RE: Modbus write error - admin - 12.02.2025
In this case you can simply ignore "illegal data value" errors. Looks like this is simply a device "feature".