Precautions - Mitsubishi Electric GOT2000 Series Connection Manual

8.6

Precautions

■1. Send delay
"Send delay" is a setting used for low-speed devices that cannot respond when the send response is too fast. When
"Send delay" is set with the GOT's communication devices detail settings, the "Send delay" is enabled for all master
devices that are connected.
■2. Errors that occur in the GOT at MODBUS/TCP slave connection
In MODBUS/TCP 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
Device reading error. Correct device.
309
*1
Device writing error. Correct device.
315
The specified device No. is out of range.
*1
322
Confirm the available device range.
*1 This may occur even when the MODBUS/TCP slave is not connected.
■3. 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
Contents of the message display
Description
A function code not
ILLEGAL FUNCTION supported by the GOT
was received.
Description
ILLEGAL DATA An out-of-range device
ADDRESS was accessed.
Description
ILLEGAL DATA An out-of-range device
ADDRESS was accessed.
The request packet
(number of write points,
number of write data
ILLEGAL DATA VALUE
bytes, and number of
write data items) is
inconsistent.
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.
Refer to the following for details on function codes
supported by the GOT.
➠
■2. Function Code
Causes
Check that the device being accessed is correct.
Causes
Check that the device being accessed is correct.
Check that a correct packet is sent from the master
equipment.
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
Countermeasures
Countermeasures
8.6 Precautions
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