28
Read Alarm or Warning (ALM_RD)
The ALM_RD command is used to read the following information about the status of faults
and alarms.
• Present fault and alarm status list
• Fault history (Alarms are not saved in the history.)
• Details of faults
In the following case, a warning is generated and the command is ignored.
• If ALM_RD_MOD is other than a set value: Data setting alarm (A.94)
The fault history is saved in EEPROM and is kept even when the control power is inter-
rupted.
The following table shows the specifications for ALM_RD_MOD and ALM_DATA.
If the fault history (ALM_RD_MOD = 1) is selected, the fault code (1 byte) is entered in
order of detection from ALM_DATA byte 6, and byte 6 is refreshed with the most recent
fault code. If no fault occurred, 00H is displayed to indicate normal operations.
Byte
Command
Response
1
ALM_RD
ALM_RD
2
ALARM
3
STATUS
4
5
ALM_RD_MOD
ALM_RD_MOD
6
ALM_DATA
7
8
9
10
11
12
13
14
15
16
WDT
RWDT
ALM_RD_MOD
ALM_DATA
Max.
Processing Time
Constant No.
0
Present fault (byte 6), past fault (byte 7)
0.1 s
n178 (Fault History)
1
Fault history (Alarms are not retained in the history.)
2 max. (bytes 6 and 7)*
0.1 s
n178
