Electro-Voice owner manual Performance Specifications, Appendix, NetMax N8000 System Controller

Appendix

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.

	Date Transmission Cable
Bus Length (in m)	Resistance per	Cable Diameter	Termination (in Ω)	Max. Data Transfer
	Unit Length			Rate
	(in mΩ/m)
0...40	< 70	0,25...0,34 mm²	124	1000 kbit/s at 40 m
		AWG23, AWG22
40...300	< 60	0,34...0,6 mm²	127	500 kbit/s at 100 m
		AWG22, AWG20
300 ... 600	< 40	0,5...0,6 mm²	150...300*	100 kbit/s at 500 m
		AWG 20
600...1000	< 26	0,75...0,8 mm²	150...300*	62,5 kbit/s at 1000 m
		AWG 18

*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 bzw. AWG24	0,34 mm² bzw. AWG22	0,34 mm² bzw. AWG22
250	0,34 mm² bzw. AWG22	0,5 mm² bzw. AWG20	0,5 mm² bzw. AWG20
500	0,75 mm² bzw. AWG18	0,75 mm² bzw. AWG18	1,0 mm² bzw. 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

0.3meter 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.

NetMax N8000 System Controller	39
Owner’s manual