Mitsubishi Electric QJ71MB91 User Manual page 104

4
MODBUS STANDARD FUNCTIONS
Figure 4.80 Communications event when switching to listen only mode
Figure 4.81 Communications event when processing restart communications option
4
- 49 4.13 Get Communications Event Log (FC: 12)
2) When sending a response message
The slave (QJ71MB91) stores the communications event log after sending the
response message.
For the relevant communications event, "1" is stored.
b7 b6 b5 b4 b3
0 1 0 0 0
Figure 4.79 Communications event at response message transmission
* 1 While the occurrence of busy status (exception code 05
protocol, "0" is stored for the QJ71MB01 because this kind of events does not occur in it.
3) When switching to the listen only mode
The slave (QJ71MB91) stores the communications event log when switching
to the listen only mode.
04 is stored to the communications event log.
H
b7 b6 b5 b4
0 0 0 0
4) When processing restart communications option
The slave (QJ71MB91) stores the communications event log when processing
the restart communications option.
00 is stored to the communications event log.
H
b7 b6 b5 b4
0 0 0 0
(b) Clearing the communications event log
The communications event can be cleared by either of the following:
Clear setting of the communications event log with the restart communications
option ( Section 4.11.2)
Power OFF ON, or programmable controller CPU reset
b2 b1 b0
0 1/0 1/0
Message error (Exception code 01
Processing interruption (Exception code 04
Unused (Fixed to 0) *
Fixed to 1
Unused(Fixed to "0")
b3 b2 b1 b0
0 1 0 0
b3 b2 b1 b0
0 0 0 0
to 03 )
H H
)
H
1
to 07 ) is stored for the MODBUS
H H