Mitsubishi QJ71MB91, User Manual

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11
- 19 11.3 Checking the Communication Status of QJ71MB91
11
TROUBLESHOOTING
(b) Slave function
* 1 Sub-functions in the table show sub-function codes of function code 8.( Section 4.11)
* 2 The NAK count defined by the MODBUS protocol is stored in the Slave NAK count.
Note that this count is different from the NAK LED on the QJ71MB91.
Table11.10 List of diagnostic counters (Slave function)
Item Description
Sub-
function*1
Buffer memory
CH1 CH2
Bus message count
Counts the number of messages sensed on the line.
The bus message count is in an exclusive relationship with
the bus communication error count.
0011
0F00
H
(3840)
0F40
H
(3904)
Bus communication error
count
Counts the number of error messages sensed on the line.
"Error messages" include the following:
• CRC/LRC error message
• Overrun/parity error
• Short frame (less than 3 bytes)
• Character overrun (256 bytes or more)
Messages other than the above are counted by the bus
message count. (The bus communication error count is in
an exclusive relationship with the bus message count.)
0012
0F01
H
(3841)
0F41
H
(3905)
Exception error count
Counts the number of times that exception errors are
occurred. (excluding broadcast communication messages)
0013
0F0A
H
(3850)
0F4A
H
(3914)
Slave message count
Counts the number of times that messages addressed to
the host were processed.
(Including when reception of broadcast request messages)
0014
0F06
H
(3846)
0F46
H
(3910)
Slave no-response count
Counts the number of times that broadcast request
messages were received.
0015
0F07
H
(3847)
0F47
H
(3911)
Slave NAK count
*2
Counts the number of times that the slave returned the
NAK response to the master.
The QJ71MB91 always stores "0".
0016
0F08
H
(3848)
0F48
H
(3912)
Slave busy count
Counts the number of times that the slave returned a busy
response to the master.
The QJ71MB91always stores "0".
0017
0F09
H
(3849)
0F49
H
(3913)
Character overrun error count
Counts the number of times that the request message size
exceeded the upper limit.
0018
0F02
H
(3842)
0F42
H
(3906)
Message discard count
Counts the number of times that request messages are
discarded, for example, due to reasons such as
processing of another request message on a slave or
reception of a request message addressed to another
station.
-
0F03
H
(3843)
0F43
H
(3907)
Data discard count
Counts the number of times that illegal data (e.g. frames
not configured in the stipulated request message format)
was discarded.
-
0F04
H
(3844)
0F44
H
(3908)
Failed transmission count
Counts the number of times that transmission of response
messages failed. (e.g. when no cable is connected)
-
0F05
H
(3845)
0F45
H
(3909)