Mitsubishi Electric 800 Series Instruction Manual page 65

Normal response (Response message)
Transaction Protocol
identifier identifier
H00
*1 *1
(8 bits)
*1 The values are the same as those in the query message.
The number of holding registers that were successfully accessed was returned as two with the start address 41007 (Pr.7).
 Error response
• An error response is returned if the query message received from the master contains an illegal function, address or data.
• Error response (Response message)
a. Transaction b. Protocol
identifier identifier
H L H
(8 bits) (8 bits) (8 bits)
Message
a Transaction identifier
b Protocol identifier
c Length field
d Unit identifier
e Function code
f Exception code
• Error code list
Code Error item
01 ILLEGAL FUNCTION
02
ILLEGAL DATA ADDRESS
03 ILLEGAL DATA VALUE
06 SLAVE DEVICE BUSY
*1 An error response is not returned in the following cases:
(a) Function code H03 (reading data of holding registers)
When the quantity of registers is specified as one or more and there are one or more holding registers from which data can be read.
(b) Function code H10 (writing data to multiple holding registers)
When the quantity of registers is specified as one or more and there are one or more holding registers to which data can be written.
In other words, when function code H03 or H10 is used and multiple holding registers are accessed, an error response is not returned even if a
nonexistent holding register or holding register that cannot be read or written from/to is accessed.
NOTE
• An error response is returned if none of the accessed holding registers exist. When an accessed holding register does not
exist, the read value is 0 and the written data is invalid.
 MODBUS register
• The following shows the MODBUS registers for system environment variables (read/write), real time monitor items (read),
parameters (read/write), fault history data (read/write), and model information monitor items (read).
• System environment variables
Register
40002 Inverter reset
40003 Parameter clear
40004 All parameter clear
40006
Parameter clear
40007
All parameter clear
Inverter status / control input command
40008
(extended)
64
2. Ethernet Communication
2.7 MODBUS/TCP
Length field Unit identifier
H00 H00 H06 HFF
(8 bits) (8 bits) (8 bits) (8 bits)
c. Length field
L H L
(8 bits) (8 bits) (8 bits)
The master adds the data for the purpose of transaction control.
The same data is returned in the response from the slave.
Fixed to 0. (When the slave receives data other than 0, it does not send the response message.)
"0" is returned in the response from the slave.
The data length from the unit identifier to the data is stored in byte.
Fixed to 255
The function code requested by the master and H80 is set.
The codes in the following table are set.
The query message from the master has a function code that cannot be handled by the slave.
The query message from the master has a register address that cannot be handled by the
*1
slave.
(No parameter, parameter cannot be read, parameter cannot be written)
The query message from the master has data that cannot be handled by the slave.
(Out of parameter write range, a mode is specified, or other error)
The request message cannot be processed because the slave is executing another operation.
Definition
*1
*1
*2
Function code
H10
(8 bits)
d. Unit
e. Function code
identifier
H80 + Function
(8 bits)
(8 bits)
Description
Error description
Read/write
Write Any value
Write Set H965A.
Write Set H99AA.
Write Set H5A96.
Write Set HAA99.
Read/write Refer to the following.
Starting
No. of points
address
H03 HEE H00 H02
(8 bits) (8 bits) (8 bits) (8 bits)
Exception code
(8 bits)
Remarks