MERCEDES ECU MR-PLD (обучения) - Автозапчасти и автоХитрости

Configuration

The electronic system is divided in two independent subsystems that can be monitored separately.

The cabin mounted control unit “FRE” (vehicle electronics) controls the sensors and actuators attached to the drivers cab or the vehicle frame and involves all functions which are relevant for the vehicle.

The engine mounted control unit MR-PLD controls all sensors and actuators attached to the engine and involves all functions which are important to the engine operation.

The two control units are connected via a bus connection with “one wire capability”. Via this bus connection nominal values and the operating mode of the engine are demanded by the respective FRE (e.g. increase of idle speed, speed-controlled engine operation with programmable desired speed, torque limitation, freely selectable control characteristic, engine braking torque etc.), and in the opposite direction the MR-PLD control unit transmits information about the actual engine operating mode to the FRE (e.g. flame start unit).

Advantages:

– the plug connections at the engine are reduced to the connections which are relevant to the engine

– the vehicle connections are located in the uncritical surrounding area of the drivers cab (high degree of acceleration- and temperature load at the engine)

– less connection lines between engine and vehicle (reduced to the EMV-uncritical CAN connection) proves to be of particular advantage in the bus (due to the great distance between the control elements and the engine, like accelerator pedal etc.)

– the computers are only burdened with the functions and tasks of the particular system (the PLD-MR computer is only responsible for the engine management, no load through vehicle functions) – a modular extension of the system is possible by means of additional units that are connected with

the bus system

Each subsystem is tuned individually and can be tested as a subsystem. Therefore the engine can be replaced by an engine of a different design but with the same category of engine performance, without having to change the configuration in the vehicle-control unit (FRE) (e.g. PLD-MR engine is replaced by

Common-Rail engine). 4-, 5-, 6-, and 8-cylinder engines can be operated with the same PLD-MR.

Accessory parts at the engine like “Waste Gate”, fan high speed etc. can be regulated, controlled and connected via 6 PWM outputs at the PLD-MR. An additional digital output is reserved for the starter control! Functional requests of other electronic systems like ABS, ASR, EPB, EAS, automatic transmission, retarder etc. (data exchange via vehicle-CAN-Bus (e.g. IES-CAN)) are coordinated in the FRE and prepared for the engine electronics (PLD-MR).

The module MR-PLD engine electronics consists of the control unit and the fuel cooling. The MR-PLD control unit consists of a component circuit board with base plate (planar technique) and a zinc pressure die casting housing. The circuit board/base plate combination is screwed to the housing. The seal between

housing and circuit board is achieved by means of a fluid gasket.

The external electrical contact is maintained via a 16 pin and a 55-pin socket. To bring the pressure inside the housing into equilibrium with the ambient pressure, a pressure sensitive membrane is located on the bottom of the housing. The housing has 4 eyelets to accommodate the damping elements and screw them onto the engine. See also chapter 3.4. Mechanical description.

Communication

The FRE makes demands on the MR-PLD via the CAN like e.g.:

- Torque demand through accelerator pedal (controlled operation i.e. normal operation)

- ADR-governor type (5 types altogether, see following chapter 3.3.10.

- in the case of ADR mode: desired speed and max. torque

The MR-PLD sends the following data to the FRE:

- Actual value (sensor values) like speed, temperature, pressure.....

- Feedback of operating mode

The starter driver has a multiple redundancy. The so-called main path consists of two transistors connected in series, which are powered by the battery voltage. In normal function the starter control takes place via this main path.

The so-called auxiliary path is powered via terminal 50 and can be released via terminal 50 in the case of a start, if e.g. the main path is defective. The auxiliary path is also used if the main controller of the engine control unit is defective. Due to the fact that the auxiliary path has no hardware short circuit protection, it is fundamentally used only after the activation of the main path, if furthermore there has been no signal detected via the main path.

The main controller can activate the main path (STA1 and STA2) and disable or release the auxiliary path (STA-NOT). A level measurement at the starter driver output (STA-level) and a short circuit detection (STAshort circuit detection) in the main path serve for the fault recognition.

Starter driver

System interface diagram

The 55 pin and the 16 pin sockets are the interfaces of the system. In the following block diagram the modules are combined in main groups. The exact pin assignment lists are on the following pages.

Interface diagram