CAN data bus, function - GF54.00-P-0005F

MODEL 124 with ENGINE 104, 111, 119 (except 104.98)

MODEL 129 with ENGINE 104, 112, 113, 119, 120 (except 104.98)

MODEL 140 with ENGINE 104, 119, 120

MODEL 163 with ENGINES 112, 113

MODEL 170 with ENGINE 111, 112 (except, 112.96)

MODEL 202 with ENGINE 104, 111, 112

MODEL 203 with ENGINE 111, 112 (except, 112.96)

MODEL 208 with ENGINES 111, 112, 113

MODEL 210 with ENGINE 104, 112, 113, 119

MODEL 215 with ENGINE 113, 137 (except 113.99)

MODEL 220 with ENGINE 112, 113, 137 (except, 113.99)

MODEL 230 with ENGINE 112, 113 (except, 113.99)

MODEL 211 with ENGINE 112, 113 (except, 113.99)

MODEL 209 with ENGINE 112, 113

Shown on example of Controller Area Network-Bus Class C (engine compartment) (CAN-C) in model 220 with engine 112, 113 and code (219) Distronic (DTR)

Fig 1: CAN Data Bus, Function Diagram

Task

Data exchange between individual control units
Readying sensor signals for several systems
Reducing the number of electrical lines
Improving electromagnetic compatibility

Design

The data bus consists of a twisted, two-core data line which connects all the participants together in a parallel circuit. The lines of the data line must not be mixed up (low level or high level). The ME-SFI [ME] control unit (N3/10) (except model 124 and model 140), the DAS [FBS] control unit (N73/1) (model 163), the DAS [FBS] radio frequency/infrared control unit (N54/4) (model 129) and the DAS [FBS] radio frequency control unit (N54/3) (model 170) apply as a terminal with regard to bus adaptation.

In each case a terminating resistor of 120 Ω is installed for this.

Exception: ME-SFI [ME] control unit (N3/10) with engine (240 Ω each).

In the case of a resistance measurement of the data line (terminal 15 OFF) the various terminating resistors are connected in parallel in the terminals.

Function

The data are transmitted digitally on the data bus at various intervals. The individual data blocks are defined in a protocol and it is specified which data are received or transmitted by a control unit. Each connected control unit is able to transmit or receive data. The sum of the data blocks, the short break between 2 transfer intervals and other properties of the data bus are checked constantly. Any faults detected are stored.

Vehicles with electronic ignition switch control unit (N73)

In the vehicle a distinction is made between a high-speed Controller Area Network bus class C (engine compartment) (CAN-C) and the 6 times slower Controller Area Network bus class B (interior) (CAN-B). The electronic ignition switch control unit (N73) forms the interface (Gateway) for this. This does not apply to vehicles with a central gateway control unit (N93) (except model 203).

Vehicles with central gateway control unit (N93)

The central gateway control unit forms the interface (Gateway) between the two data buses (N93) (except model 203). The central gateway control unit (N93) serves as the interface for STAR DIAGNOSIS for all model series.

The new control unit must be coded again when exchanging a control unit. The control unit can be coded via a menu in the hand-held tester (up to 07/99) or via STAR DIAGNOSIS.

CAN data bus, function		GF54.00-P-0005A
Networking, general	Model 202 as of 1.6.97	GF54.21-P-9611C
	Model 210 as of 1.3.97 (except 210.081/281)
	Model 210.081/281
Overall network (GVN) function	Model 215, 220 up to 31.8.03	GF00.19-P-0001S
	Model 215, 220 as of 1.9.03	GF00.19-P-0001SX
	Model 203 up to 23.4.04	GF00.19-P-0001PP
	Model 203 as of 24.4.04	GF00.19-P-0001PM
	Model 209 up to 31.5.04	GF00.19-P-0001Q
	without code (491) USA version and without code (498) Japan version
	Model 209 up to 31.5.04 With code (498) Japan version	GF00.19-P-0001QJ
	Model 209 up to 31.5.04 With code (491) USA version	GF00.19-P-0001QU
	Model 209 as of 1.6.04	GF00.19-P-0001QM
	Model 230 up to 31.5.04 except code (494) USA version except code (498) Japanese version	GF00.19-P-0001R
	Model 230 up to 30.6.04 with CODE (494) USA version except code (498) Japanese version
	Model 230 as of 1.6.04 except code (494) USA version except code (498) Japanese version	GF00.19-P-0001RM
	Model 230 as of 1.7.04 with CODE (494) USA version
	Model 211.0/2	GF00.19-P-0001T