110
Response Codes
Section 6-4
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
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 com-
puter returning the response. Refer to the operation manual for the device
returning the response for details when troubleshooting the error.
6-4-2
Network Relay Errors
A network relay error will occur whenever a command cannot reach the desti-
nation. These errors can occur for several reasons: 1) Data was not success-
fully 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 response code, should enable you to track the error.
Error network address: 00 to 7F (Hex) (0 to 127 in decimal)
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)
Relay Errors
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 Example 2, the relay error occurs because either the specified
destination node or the next relay node does not exist.
In the two diagrams, the numbers indicate the following:
(1) The transmitted data fails to be received.
(2) The relay error and response code are returned to the command
source.
Bit
1: PC
N
on-fatal Error Flag
1: PC Fatal Error Flag
Error network address Error node address
First word
Second word
Third word
Command code
1: Relay Error Flag
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
First byte
Second byte
Sub response code (SRES)
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
Main response code (MRES)
Содержание SYSMAC 3G8F7-CLK12-EV1
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