UMAX180800, 20 Thermocouple, 2 RTD, 4 Inputs, 6 Relays Dual CAN Controller
Version 1
Page: 33-71
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 30. If the FMI is changed, the OC of the associate error log is automatically reset to
zero.
Table 30. Low Fault FMI versus High Fault FMI
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
If the FMI used is anything other than one of those in Table 30, then both the low
and the high faults will be assigned the same FMI. This condition should be
avoided, as the log will still use different OC for the two types of faults, even though
they will be reported the same in the DTC.
When the fault is linked to a DTC, a non-volatile log of the occurrence count (OC) is kept. As
soon as the controller detects a new (previously inactive) fault, it will start decrementing the
Delay Before Sending DM1
timer for the Diagnostic function block. If the fault has remained
present during the delay time, then the controller will set the DTC to active, and it will
increment the OC in the log. A DM1 will immediately be generated that includes the new DTC.
The timer is provided so that intermittent faults do not overwhelm the network as the fault
comes and goes, since a DM1 message would be sent every time the fault shows up or goes
away.
3.15 J1939 Network
The
J1939 Network
function block defines the global J1939 CAN bus settings. It does not have
signal inputs and outputs.
