PowerH SERIES

Performance Specifications

According to the ISO 11898-2 standard, CAN-bus data transfer cabling has to be carried out using Twisted- Pair cables with or without shielding providing a characteristic impedance of 120 Ω. Both ends of a CAN- bus need to be terminated with 120 Ω termination-plugs. The maximum bus-length depends on the actual data transfer rate, the kind of data transfer cable being used, as well as the total number of participants on the bus. The following table shows the most essential requirements for CAN-networks consisting of up to 64 participants.

 

Data Transmission Cable

 

 

Bus Length

Resistance per Unit

 

Termination (in Ω)

Max. Data Transfer Rate

(in m)

Length

Cable Diameter

 

 

 

(in mΩ/m)

 

 

 

0...40

< 70

0,25...0,34 mm²

124

1000 kbit/s

AWG23, AWG22

at 40 m

 

 

 

 

 

 

 

 

40...300

< 60

0,34...0,6 mm²

127

500 kbit/s

AWG22, AWG20

at 100 m

 

 

 

 

 

 

 

 

300...600

< 40

0,5...0,6 mm²

150...300*

100 kbit/s

AWG 20

at 500 m

 

 

 

 

 

 

 

 

600...1000

< 26

0,75...0,8 mm²

150...300*

62,5 kbit/s

AWG 18

at 1000 m

 

 

 

 

 

 

 

 

*With longer cables and many participants on the CAN-bus, termination resistors with higher impedance than the specified 120 Ω are recommended to reduce the ohmic load of the interface drivers and therefore the voltage drop between the two cable-ends.

The following table is meant for first assessment of necessary cable diameters for different bus lengths and bus-participant numbers.

Bus Length (in m)

 

Number of Units on the CAN-Bus

 

32

 

64

 

100

 

 

 

100

0,25 mm² / AWG24

 

0,34 mm² / AWG22

 

0,34 mm² / AWG22

 

 

 

 

 

 

250

0,34 mm² / AWG22

 

0,5 mm² / AWG20

 

0,5 mm² / AWG20

 

 

 

 

 

 

500

0,75 mm² / AWG18

 

0,75 mm² / AWG18

 

1,0 mm² / AWG17

 

 

 

 

 

 

Additionally, the length of branch lines - for participants that are not directly connected to the CAN-bus - is also of importance. For data transfer rates of up to 125 kbit/s, the maximum length of a single stub cable should not exceed 2 meters. For higher bit rates a maximum length of only 0.3 meter is still permissible. The entire length of all branch lines should not exceed 30 meters.

General Note:

As long as only short distances (up to 10 meters) are concerned, common RJ-45 patch cables with a characteristic impedance of 100 Ω (AWG 24 / AWG 26) can be used for the cabling inside of a rack mounted system.

The previously outlined guidelines for network cabling are mandatory as far as the rack mounted shelve interconnection or fixed installations are involved.

44 Owner’s Manual

Page 44
Image 44
Dynacord H 2500, H 5000 owner manual Performance Specifications