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Response Codes
6-4-1 Configuration
6-4-2 Network Relay Errors
First word
Second word
Third word
Relay Errors
Response codes for FINS commands consist of two bytes that indicate the result
of executing a command. The structure of the response codes is shown in the
following diagram.
Bit
7
6
Main response code (MRES)
1: Relay Error Flag
The main response code (MRES) in the first byte classifies the response and the
sub-response code (SRES) in the second byte indicates details under the
MRES classification.
If bit 7 of the first byte is ON, a network relay error has occurred. Refer to 6-4-2
Network Relay Errors for details on troubleshooting the error.
If bit 6 or 7 of the second byte is ON, an error has occurred in the PC or computer
returning the response. Refer to the operation manual for the device returning
the response for details when troubleshooting the error.
A network relay error will occur whenever a command cannot reach the destina-
tion. These errors can occur for several reasons: 1) Data was not successfully
passed between two Link Units, 2) Data was not passed successfully between a
Link Unit and another Unit, such as the PC's CPU Unit, or 3) The destination of a
gateway does not exist. In any case, the Unit that was not able to transfer data
will return a response indicating a network relay error.
Bit 7 of the first byte of the response code will be ON if a network relay error has
occurred. When this happens, two more bytes of data will follow the response
code to indicate the location of the error. This information, along with the re-
sponse code, should enable you to track the error.
First byte
Bit
7
6
5
4
3
7
6
5
4
3
Main response code (MRES)
1: Relay Error Flag
7
6
5
4
3
Error network address
Error network address: 00 to 7F (Hex) (0 to 127 in decimal)
Error node address:
A relay error indicates that the command did not reach the Unit to which it was
sent. There are two types of situation in which this can occur. Example 1 (below)
shows a situation in which a relay error occurs when data cannot be transferred
from one Communications Unit to another in an interconnected network. In Ex-
ample 2, the relay error occurs because either the specified destination node or
the next relay node does not exist.
First byte
5
4
3
2
1
0
Second byte
2
1
0
7
6
5
4
Command code
2
1
0
7
6
5
4
Sub response code (SRES)
1: PC Non-fatal Error Flag
1: PC Fatal Error Flag
2
1
0
7
6
5
4
Error node address
Controller Link: 01 to 3E (Hex) (1 to 62 in decimal)
SYSMAC NET: 01 to 7E (Hex) (1 to 126 in decimal)
SYSMAC LINK: 01 to 3E (Hex) (1 to 62 in decimal)
Section
Second byte
7
6
5
4
3
2
1
Sub-response code (SRES)
1: PC Non-fatal Error Flag
1: PC Fatal Error Flag
3
2
1
0
3
2
1
0
3
2
1
0
6-4
0
97
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Troubleshooting
