Honeywell CM4 - Get Fault History - 0 X3 D

23 Rev. 2.4 (3/05)
Honeywell Analytics CM4 Protocol Manual
Get Fault History This command will query the unit for the latest
- 0x3D fault(s). There can be as many as four and as few
as zero faults. General system faults are indicated
by bit 0 of the point status byte. If bit 0 is set to 1,
bits 1-2 should be ignored. The point status byte is
invalid for Fault 17 (Voltage Fail) and Fault 18
(Relay Fail).
Command packet to instrument:
Command Code (0x3D) - 1 byte
Response packet from instrument:
Command Code (0x3D) - 1 byte
CM4 Date - 2 bytes
CM4 Time - 2 bytes
# of faults - 1 byte (0-4 maximum)
(fault data, maximum of four possible)
Date of fault - 2 bytes
Time of fault - 2 bytes
Fault # -1 byte
Point Status -1 byte
bit 0: General fault bit
0 = point specic
1 = general
bits 1-2: Point # where fault
occurred (ignored if bit 0 is 1 and for
Faults 17 and 18)
00 = Point 1
01 = Point 2
10 = Point 3
11 = Point 4
bits 3-5: Undened
bit 6: Previously Read
0 = new (not previously read)
1 = old (previously read)
bit 7: Instrument Fault
0 = maintenance fault --
the CM4's ability to monitor
is not compromised.
1 = instrument fault -- the
CM4's ability to monitor is
compromised.