Table of Contents
Error Codes
The following table shows MODBUS communications error codes.
Error Code
Function code error
01H
A function code other than 03H, 08H, or 10H has been set by the PLC.
Invalid register number error
02H
• The register address you are attempting to access is not recorded anywhere.
• With broadcast sending, a start address other than 0000H, 0001H, or 0002H has been set.
Invalid quantity error
03H
• The number of data packets being read or written is outside the range 1 to 16.
• In write mode, the number of data packets in the message is not No. of packets x 2.
Data setting error
• A simple upper limit or lower limit error has occurred in the control data or when writing parame-
21H
ters.
• When writing parameters, the parameter setting is invalid.
Write mode error
• Attempting to write parameters from the PLC during operation.
• Attempting to write via ENTER commands from the PLC during operation.
22H
• Attempting to write parameters other than A1-00 to A1-05, E1-03, or 02-04 when warning alarm
CPF03 (defective EEPROM) has occurred.
• Attempting to write read-only data.
Writing during main circuit undervoltage (UV) error
23H
• Writing parameters from the PLC during UV (main circuit undervoltage) alarm.
• Writing via ENTER commands from the PLC during UV (main circuit undervoltage) alarm.
Writing error during parameter processing
24H
Attempting to write parameters from the PLC while processing parameters in the Drive.
Slave Not Responding
In the following cases, the slave will ignore the write function. If the slave address specified in the command
message is 0, all slaves execute the write function, but do not return response messages to the master.
When a communications error (overrun, framing, parity, or CRC-16) is detected in the command message.
•
When the slave address in the command message and the slave address in the Drive do not agree.
•
When the data that configures the message and the data time length exceeds 24 bits.
•
When the command message data length is invalid.
•
Application Precautions
Set a timer in the master to monitor response time from the slaves. Make the setting so that if no response is
sent to the master from the slave within the set time, the same command message is sent again from the mas-
ter.
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Troubleshooting
