6.3 Modbus Communications
212 SIEPCYEUOQ2V01A Q2V Technical Manual
■ No Response from Slave
The slave ignores the command message from the master and will not send a response message in these
conditions:
• When a communications error (overrun, framing, parity, CRC-16) is detected in the command message.
• When the slave address in the command message and the slave address for the drive side do not agree (Use H5-
01 [Mbus Address] to set the slave address of the drive)
• When the time interval between the data of which the message is composed is longer than 24 bits
• When the data length for the command message is not accurate
Note:
• If the keypad shows CALL [Serial Comm Transmission Error], refer to “Troubleshooting” to remove the cause of the error, and try to
do communications again. If the keypad does not show CALL, check U1-19 [Modbus Err.Code] for the error and error type.
• If you execute the write function code when the slave address in the command message is 00 (Hex.), all of the slaves will execute the
write command, but they will not send response messages to the master.
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