VFD68 Variable Frequency Drives
102
Error Response
An error response is returned if the query message received from the master has an illegal function, address,
or data. No response is returned for a parity, CRC, overrun, framing, or busy error.
Note:
No response message is sent in the case of broadcast communication.
Note:
An error occurs if all accessed holding registers do not exist.
Note:
Data read from a nonexistent holding register is 0, and data written there is invalid.
Message Data Mistake Detection
To detect the mistakes of message data from the master, error items are checked for the errors in Table 121. If
an error is detected, a trip does not occur.
Table 118: Error Response (Response Message)
Slave Address
Function
Exception Code
CRC Check
(8 bit)
H80 + function (8 bit)
(8 bit)
L (8 bit)
H (8 bit)
Table 119: Error Response (Response Message)
Message
Setting Description
Slave Address
Address received from the master.
Function
Master-requested function code + H80
Exception Code
Table 120: Error Code List
Code
Error Item
Error Description
01
Illegal Function
The set function code in the query message from the master cannot be processed by
the slave.
02
Illegal Data Address
1
1.
An error does not occur in the following cases:
a. Function code H03 (Read holding register data) - when the number of points is 1 or more and there is one or more
holding registers from which the data may be read.
b. Function code H10 (write multiple holding register data) - when the number of points is 1 or more and there is one or
more holding registers to which the data may be written.
When the function code H03 or H10 is used to access multiple holding registers, an error does not occur if a
nonexistent holding register, read-disabled register, or write-disabled register is accessed.
The set register address in the query message from the master cannot be processed
by the slave.
03
Illegal Data Value
The set data in the query message from the master cannot be processed by the slave.
Table 121: Message Data Mistake Detection
Error Item
Error Description
VFD Operation
Parity Error
The data received by the VFD differs from the specified parity
(P.120 setting).
1. P.343 increases by 1
at the error
occurrence.
2. The terminal LF is
output at an error
occurrence.
Framing Error
The data received by the VFD differs from the specified slop bit
length (P.120).
Overrun Error
The following data was sent from the master before the VFD
completes receiving data.
Message Frame Error
The message frame data length is checked, and the received
data length of less than 4 bytes is regarded as an error.
CRC Check Error
A mismatch found by CRC Check between the message frame
data and calculation result is regarded as an error.
