MELSEC - Troubleshooting
Troubleshooting of Mitsubishi MELSEC instances and items
You most likely encountered some problems with connecting to your Mitsubishi MELSEC device and you ended up here.
This article will describe some of the most common faults encountered when trying to connect and exchange data with your MELSEC device. All the various error messages is also explained here.
Error messages
Both instance and items can have errors. The following sections describes the error and how to solve them.
Instance
The instance errors are related to the connectivity status of the connector to the PLC. These errors are shown in SIA's web interface.
| Error message | Solution |
|---|---|
| The request cannot be executed to the CPU module. |
|
| Not connected to Melsec PLC |
|
| Invalid port or IP |
|
| Mode mismatch. Select binary |
|
| Mode mismatch. Select ASCII |
|
| Select A or FX or 1E model |
|
| ASCII code data that cannot be converted to binary code was received from an external device |
|
Notes
- Writing anything else than a integer value to a bit device (not a dot notated memory address.) is the same as writing the value 0
- Writing any integer value to a bit device is the same as writing the value 1
- Writing any value that is not in-between the boundaries of the valid values will not be written to the PLC.
- Creating a bit type item that points to a non-existing bit in the word (i.e. memory address D100.567) will not be written to the PLC.