UMAX180800, 20 Thermocouple, 2 RTD, 4 Inputs, 6 Relays Dual CAN Controller
Version 1
Page: 32-71
OC
Occurrence Count
(7 bits, number of times the fault has
happened)
In addition to supporting the DM1 message, the Controller also supports
DM2 Previously Active Diagnostic Trouble Codes
Sent only on request
DM3 Diagnostic Data Clear/Reset of Previously Active DTCs
Done only on request
DM11 Diagnostic Data Clear/Reset for Active DTCs
Done only on request
So long as even one Diagnostic function block has
Event Generates a DTC in DM1
set to
true, the Controller will send the DM1 message every one second, regardless of whether there
are any active faults, as recommended by the standard. While there are no active DTCs, the
Controller
will send the “No Active Faults” message. If a previously active DTC becomes
inactive, a DM1 will be sent immediately to reflect this. As soon as the last active DTC goes
inactive, it will send a DM1 indicating that there are no more active DTCs.
If there is more than on active DTC at any given time, the regular DM1 message will be sent
using a multipacket Broadcast Announce Message (BAM). If the controller receives a request
for a DM1 while this is true, it will send the multipacket message to the Requester Address
using the Transport Protocol (TP).
At power up, the DM1 message will not be broadcast until after a 5 second delay.
This is done to prevent any power up or initialization conditions from being
flagged as an active error on the network.
The Diagnostic function block has a setpoint
Event Cleared Only by DM11
. By default, this is
set to false, which means that as soon as the condition that caused an error flag to be set goes
away, the DTC is automatically made Previously Active, and is no longer included in the DM1
message. However, when this setpoint is set to true, even if the flag is cleared, the DTC will
not be made inactive, so it will continue to be sent on the DM1 message. Only when a DM11
has been requested will the DTC go inactive. This feature may be useful in a system where a
critical fault needs to be clearly identified as having happened, even if the conditions that
caused it went away.
In addition to all the active DTCs, another part of the DM1 message is the first byte, which
reflects the Lamp Status. Each Diagnostic function block has the setpoint
Lamp Set by Event
in DM1
which determines which lamp will be set in this byte while the DTC is active. The
J1939 standard defines the lamps as ‘
Malfunction’
, ‘
Red Stop’
, ‘
Amber,
Warning’
or
‘Protect’
.
By default, the
‘Amber, Warning’
lamp is typically the one set by any active fault.
By default, every Diagnostic function block has associated with it a proprietary SPN. However,
this setpoint
SPN for Event used in DTC
is fully configurable by the user should they wish it to
reflect a standard SPN define in J1939-71 instead. If the SPN is change, the OC of the
associate error log is automatically reset to zero.
