Central gateway control unit, component description - GF54.21-P-4170SX

MODEL 221.0 /1, 216.3 up to Model Year 8 

Shown on model 221.0 

Location 

The central gateway control unit is located behind the footwell cover on the cockpit cross member on the left in the direction of travel.

Task 

The central gateway control unit contains

• the gateway function between
  • central CAN
  • interior CAN
  • chassis CAN
  • diagnostic CAN
  • front end CAN
• system diagnosis
• maintenance computer
• maintenance interval display
• data container (production data memory)
• variant coding
• monitoring of bus idle

EIS 

The central gateway control unit is the interface of the CAN buses listed above, and its task is to transmit data from one CAN bus to other CAN buses.

Data transfer rates of bus systems 

• Central CAN: 500 kbit/s
• Interior CAN: 125 kbit/s
• Chassis CAN: 500 kbit/s
• Diagnostic CAN: 500 kbit/s
• Front end CAN: 500 kbit/s

System diagnosis 

The system diagnosis is integrated as a software module in the central gateway control unit. Several on-board functions are realized by the central gateway control unit for off-board diagnosis:

• CAN line diagnosis
• CAN SPECIFIED/ACTUAL configuration
• Data logger for telediagnosis

Service processor 

The maintenance computer is integrated into the central gateway control unit and uses the measured values or data of the read-only memory to determine the next due service date. Here the mileage and time-dependent variables are calculated with each other; and it remains possible to configure different vehicle uses. The maintenance interval display provides the maintenance computer with data on the condition of the engine oil.

Data container 

The data container in the central gateway control unit represents a non-volatile mobile data memory with a total capacity of 128 bytes. During vehicle production the data container has vehicle or control-unit specific data written to it, e.g. production number, test status or subtests that were not conducted. These data are used to monitor the test sequence control.

Version coding 

The central gateway control unit routes global information such as model series and national version over the various CAN buses to the networked control units. These data are processed cyclically by the central gateway control unit on the CAN buses. The control units perform part of their configuration process to match this information.

Monitoring of bus idle 

Determines the control units that maintain bus activity at expected bus idle. This information is filed in a non-volatile memory. Therefore, after a battery has discharged and the control units have been reset, it is still possible to determine whether the battery discharge was caused by the network or by individual bus users.

Discrete inputs 

• Circuit 30
• Circuit 31