Rockwell-automation 1760-xxxx Pico GFX-70 Controllers User Manual Uživatelský manuál stáhnout pdf (Strana 321)

Publication 1760-UM002B-EN-P - March 2005

Pico-Link and Point-to-Point Serial Connections 6-15

Network Transmission Security

The Pico-Link is a CAN-based network. CAN is used in cars and commercial

vehicles in all areas. The same fault recognition capability with data transfer

applies as with CAN. A BOSCH study relating to undiscovered and corrupt

messages determined the following:

The probability of non-discovery of a corrupted message (residual error

probability) is: < 10

-10

message error rate.

The message error rate depends on:

• Bus loading

• Telegram length

• Malfunction frequency

• Number of stations

Example:

Network with:

• 500 kBaud

• average bus load 25%

• average operating time 2000 h/year

• average error rate of 10

-3

,

i.e.: 1 message is faulty every 1000

• transmission of 1.12 x 10

10

messages per year of which 1.12 x 10

7

messages are faulty

• residual error probability: r < 10

-10

x 10

-3

= 10

-13

This means: one of 10

13

messages is so corrupt that the fault cannot be

recognized as such. For a network, this corresponds to a working time of

approximately 1000 years.

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