Yaskawa F7 Modbus - Manual (Page 27)

Message Formats 2-10
No Response
The slave disregards the command message and does not return a response message in the following cases:
1. In simultaneous broadcasting of data (slave address field is 0), all slaves execute.
2. When a communication error (overrun, framing, parity, or CRC-16) is detected in the command message.
3. When the slave address in the command message does not coincide with the address set in the slave.
4. When it takes longer than 2 seconds to send a message.
5. When the time interval between characters exceeds 3.5 ms
6. When the command message data length is not proper.
Error Codes
Table 2-14 – Fault Codes
Code Fault Description
1 Function error Invalid or unsupported function code in command message
2 Invalid Register Invalid register address
3 Invalid Number of Registers Invalid command message quantity
21 Data Limits Exceeded The write command message data is out range for the requested register
22 Write Failure The register to be written is write protected