Precautions - Mitsubishi Electric GOT2000 Series Connection Manual

7.7

Precautions

■1. Errors that occur in the GOT at MODBUS/RTU slave connection
In MODBUS/RTU slave connection, contents of the message display, causes, and countermeasures when an error
occurs in the GOT are described below. When the following errors occur, the GOT will generate a system alarm.
Error code
*1
309
*1
315
*1
322
*1
■2. Error codes (MODBUS Exception Codes) returned from GOT (slave) to MODBUS master
equipment
The GOT (slave) supports the following error codes (MODBUS Exception Codes) in respect to the request from the
MODBUS master equipment. When the following errors occur, the GOT will not generate a system alarm.
The description, causes and countermeasures for each error code are explained below.
(1) Error codes issued in common in respect to request from master equipment
Error code
Category
(HEX)
0x01
(2) Error code issued in response to read request from master equipment
Error code
Category
(HEX)
0x02 Read/Write
(3) Error code issued in response to write request from master equipment
Error code
Category
(HEX)
0x02 Read/Write
0x03 Write
(4) Error code issued when diagnosis occurs (function code 0x08)
Error code
Category
(HEX)
0x01
7 - 16
7.7 Precautions
Contents of the message display
Device reading error. Correct device.
Device writing error. Correct device.
The specified device No. is out of range.
Confirm the available device range.
This may occur even when the MODBUS/RTU slave is not connected.
Description
- ILLEGAL FUNCTION
Description
ILLEGAL DATA
ADDRESS
Description
ILLEGAL DATA
ADDRESS
ILLEGAL DATA VALUE
Description
- ILLEGAL FUNCTION
Causes
• An error occurred when reading
consecutive devices.
• A device that is out of the monitor
range is specified at a place where
consecutive device is specified, such
as graph function or system
information.
• Writing was executed to a device No.
that is out of the monitor range.
• Writing was executed to a write-
prohibit device.
• A device read error occurs.
• The GOT accesses the device that is
out of range specified by the master
station.
Causes
Use only function codes supported by GOT.
A function code not
Refer to the following for details on function codes
supported by the GOT
supported by the GOT.
was received.
➠
Causes
An out-of-range device
Check that the device being accessed is correct.
was accessed.
Causes
An out-of-range device
Check that the device being accessed is correct.
was accessed.
The request packet
(number of write points,
number of write data Check that a correct packet is sent from the master
bytes, and number of equipment.
write data items) is
inconsistent.
Causes
The GOT received an
unsupported sub-function Use only 0x0000 (loopback) for the sub-function codes.
code.
Countermeasures
Correct so that a device No. in the
monitor range is specified.
Review the write target device and the
device No.
To take corrective actions, check the
range that is allocated to the master
station and range of the monitoring
target device.
Countermeasures
■2. Function Code
Countermeasures
Countermeasures
Countermeasures