SG_FSE_SiplaceHF_HF3_00193901-05_eng - 第84页

1 - 14 S tudent Guide SIPLACE HF/HF3 3 Communication and Control Edition 09/2005 14 Arbitration: st ate of matter diagram 3 Fig. 3.3 - 9 flow chart bus arbitration There are two bus states, called ’dom inant’ and ’recess…

1 - 13

Student Guide SIPLACE HF/HF3

Edition 09/2005 3 Communication and Control

3.3.2.3 CSMA: Collusion Detectection

When the bus is free any unit may start to transmit a message. The unit with the message of the

highest priority is at first.

Fig. 3.3 - 8 CSMA: collusion detection

3.3.2.4 CAN Bus Arbitration

In CAN networks, there is no addressing of subscribers or stations in the conventional sense, but

instead, prioritized messages are transmitted. A transmitter sends a message to all CAN nodes

(broadcasting). Each node decide on the basis of the identifier received whether it should process

the message or not. The identifier determines the priority that the message enjoys in competition

for bus access. The relatively simplicity of the CAN chips interlaces make applications program-

ming relatively simply.

Whenever the bus is free, any unit may start to transmit a message. If 2 or more units start trans-

mitting messages at the same time, the bus access conflict is resolved by bitwise arbitration using

IDENTIFIER.

The mechanism of arbitration guarantees that neither information nor time is lost. A DATA FRAME

prevails over the REMOTE FRAME. During arbitration every transmitter compares the level of the

bit transmitted with the level that is monitored on the bus. If these levels are equal the unit may

continue to send. When a recessive level is sent and a dominant level is monitored, the unit has

lost arbitration and must withdraw without sending one more bit.

Multi master:

When the bus is free any unit may start to transmit a message. The unit with the message of the

highest priority is transmitted at first.

bus access

low waiting time

for high prioritized

telegrams

CSMA / CD: Carrier Sense Multiple Access by Collusion Detection

in case of collusion,

the members with

the lower priority

start again later

Carrier Sense

Multiple Access

(CSMA)

ollision

Detection

(CD)

1 - 14

Student Guide SIPLACE HF/HF3

3 Communication and Control Edition 09/2005

Arbitration: state of matter diagram 3

Fig. 3.3 - 9 flow chart bus arbitration

There are two bus states, called ’dominant’ and ’recessive’. The bus logic uses a ’Wired-AND’

mechanism, that is,

’dominant bits’ (equivalent to the logic level ’zero’) overwrite the ’recessive

bits’

(equivalent to the logic level ’one’).

Example: Arbitration with bit by bit detection of 2 member.

Fig. 3.3 - 10 CAN- bus arbitration with 2 member

waiting if bus is free

bit SoF

bus in receiving state

1st bit of arbitration

transmitted

compare transmitted bit

level with bus level

bus in error state

arbitration lost?

recessive bit on dominant bus state

all arbitration bits are transmitted,

send control field and data field

next bits

START: Any member

will send a message

11 10 9 8 7 6 5 4 3 2 1 0

recessive (logical high)

dominant (logical low)

member 1 wins arbitration here

member 2 looses arbitration here

and switch in receiving state

identifier member 1 1

Bit

identifier member 2 2

1 - 15

Student Guide SIPLACE HF/HF3

Edition 09/2005 3 Communication and Control

3.3.3 CAN Bus Concept on HF machine(up to MA.No. xx)

The placement machine SIPLACE HF uses a bus system with 1 Mbit/s transmission rate.The

CAN: Bus system begin at the Communication board and is split in 2 path. Every path is termi-

nated by a 120 ohm terminator on the CAN Bus board at the individual placement head.

Fig. 3.3 - 11 CAN Bus overall overview (new circuit diagrams)

Please Note: At SC/MC 505 update the gantry2 name change to gantry 3!!

The CAN- Wiring is changed that the cable went from COT3 to Gantry 3 and from Transport con-

trol to Gantry 1!! The CAN-Bus system is splited to 2 CAN-systems mean the second connector

at COMboard 1 is connected to COM 2!!

SMP BUS

Trailing cable-

Interface

Gantry 1

Trailing cable-

Interface

Gantry 2 *

CAN Bus cable 2

COT 3

Tape cutter

CAN Bus cable 1

Computer Unit

* SW Update 504 --> 505 Gantry 2 will be changed to gantry 3

old cable loop!

new circuit diagram!

Transport

Control

unit

COT 1

Tape cutter

Axis unit

PA 2

Vision

Section 2

CAN I/O

Main Module

Main Distributer Sektor 4

Control unit

Section 2

CAN E/A

Modul

Sektor 4

CAN E/A

Modul

Sektor 4

CAN E/A

Modul

Sektor 4

CAN I/O

SUB Module

Section 4

Vision

Control unit

SUB Distributor Section 4

Section 4

COT 2 / MTC

Tape cutter

COT 4 / MTC

Tape cutter

COM Unit

(left)

COM Unit

(right)