UM AX032200 Version 1.0 13-46
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.
Every Diagnostic function block also has associated with it a default FMI. The only setpoint for the
user to change the FMI is
FMI for Event used in DTC
, even though some Diagnostic function
blocks can have both high and low errors. In those cases, the FMI in the setpoint reflects that of
the low-end condition, and the FMI used by the high fault will be determined per Table 10. If the
FMI is changed, the OC of the associate error log is automatically reset to zero.
FMI for Event used in DTC
– Low Fault Corresponding FMI used in DTC – High Fault
FMI=1, Data Valid But Below Normal
Operational Range
– Most Severe Level
FMI=0, Data Valid But Above Normal
Operational Range
– Most Severe Level
FMI=4, Voltage Below Normal, Or
Shorted To Low Source
FMI=3, Voltage Above Normal, Or Shorted To
High Source
FMI=5, Current Below Normal Or Open
Circuit
FMI=6, Current Above Normal Or Grounded
Circuit
FMI=17, Data Valid But Below Normal
Operating Range
– Least Severe Level
FMI=15, Data Valid But Above Normal
Operating Range
– Least Severe Level
FMI=18, Data Valid But Below Normal
Operating Range
– Moderately Severe
Level
FMI=16, Data Valid But Above Normal
Operating Range
– Moderately Severe Level
FMI=21, Data Drifted Low
FMI=20, Data Drifted High
Table 9: Low Fault FMI versus High Fault FMI
