This outputs have Two different functions, it may be used as:
1- Sensor Supply output
This function is common for all SENSOR SUPPLY outputs of the POWER ECU (more Details ).
2- Oil Level measurement
This document aims at describing how the Oil level measurement is
processed on ActiMux Power ECU.
It intends to provide help for application design under ActiGraf.
Oil level measurement function is allowed on Power ECU Sensor Power
Supply output.
Measurement principle consists in supplying a stabilized current to an
"hot wire" sensor and to process 2 measurements of the delivered
voltage.
Measurements are separated by a user-defined time interval that is
accurate enough to guarantee measurement reproducibility.
ActiGraf offers an interface to 2 parameters : "Measure Interval " and
" Generated Current " that should be adapted to the sensor
characteristics.
Three variables are also used : "Voltage difference", "Start Measure"
and " Measure Ready ".
Measurement process is activated by a rising edge on the "Start Measure
" variable. First, a current which value has been set thanks to
parameter "Generated current" is supplied to the sensor and the flag "
Measure Ready " is reset to 0. After a constant stabilisation time,
voltage measurement 1 is processed. Voltage measurement 2 is processed
after that a period of time length defined by "Time Interval " user
parameter has been elapsed.
Supplied current is then shut down. Once voltage difference is
available through the " Voltage difference " variable, "Measure Ready "
flag is finally set to 1.
If an error occurred during acquisition process or value calculation, "
Measure Ready "stays low.
Measurement relaunch operation is done by a toggling sequence on "Start
Measure " command bit (new rising edge applied to the command).
Due to "hot wire" measurement method, consecutive measurement should be
implemented with caution to sensor post-heat time.
2.1-Parameters
The following parameters are to be set for the oil measurement function :
| Category | parameter | Description |
|---|---|---|
| General | 'Mode' |
set the function of the output |
| Delta time measurement | define the time separating hot measure and cold measure | |
| current generated | set the value of supplied current | |
| 'Recurr. period: Frame ANA_F2 |
This parameter set the recurrence of the frame ANA2 sent by the Power ECU indicating the status of it's analogue inputs. This parameter is common for the oil measurement function and all UIN inputs used as analogue inputs. This frame is carrying the UIN Resistance or voltage values for UIN inputs. And the voltage difference for sensor supply output. The resolutions are : |
2.2-Mnemonics
The mnemonics names for Powers ECU IO must applies a set of rules more details.
The following mnemonics are available for the sensor supply function:
| Mnemonic | STraToN Type | Description |
|---|---|---|
| 'Voltage_difference' |
WORD | analogue input indicating the voltage difference |
| 'Start_Measure' |
BOOL | variable used to control the start of the process measurement |
| 'Measure_Ready' |
BOOL | To check if the measure is done and the voltage difference value is available. |
