85
6 Useful Functions
85
Useful Functions
Chapter
6
12 (0x0C) Get Comm Event Log
This function is for reading the event status from slave devices.
The contents of the status and the event counter are the same as status 11 (Get Comm Event Counter).
Message count is the same as sub-function 11 (Return Bus Message Count) of status 08. The event log
retains 64 bytes worth of messages communicated by the slave device.
The newest event is always the
0th byte, and old events are discarded when it exceeds 64. The detailed
contents of the events will be defined later on.
* N = Number of events + (3 x 2)
Example) Reading the event status.
The example shows 264 times for the event counter (0x0108), 289 times for the message counter
(0x0121), and not busy (0x0000). The newest event is 11000000 (0xC0) and bit 6 is 1,which means
that the broadcast was rece
ived. The previous event is 00, indicating that the slavedevice received a
request for Communications Restart.
[Request]
Function 1 byte 0x0C
[Response]
Function 1 byte 0x0C
Byte count 1 byte N *
Status 2 bytes 0x0000
Event counter 2 bytes 0x0000 to 0xFFFF
Message count 2 bytes 0x0000 to 0xFFFF
Event counter n bytes 0 to 64 (number of events)
[Error response]
Error code 1 byte 0x8C (Function +0x80)
Exception code 1 byte 01
[Request]
Function 0C
[Response]
Function 0C
Byte count 08
Status (HI) 00
Status (LO) 00
Event counter (HI) 01
Event counter (LO) 08
Message count (HI) 01
Message count (LO) 21
Event 0 C0
Event 1 00
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