Siemens FC700A manual Bus overview, Rd = Ri x 3,65 45Ω < Ri < 200Ω, Bus systems

							Bus systems
6.1	Bus overview
Features		C-Bus	I-Bus	SynoLOOP	SynoLINE600	LON-Bus	Data Bus
Field of applica-						Local data bus	Local data bus
tion				For addressable	For collective		parallel ind.
		Local system bus	Inside control unit			for floor indicator
				detectors	detectors		panel, synoptic
						panels
							panel or relay
Speed of trans-		57kBaud	1000kBaud	2 messages/sec	(Direct current	78kBaud	SPI-Bus 2KHz
mission					signal)
Length of line		Max. 1000m	Max. 3m (only		Max.	Max. 500m as
				Max. 150Ω/300nF		free topology	Max. 1000m
					150/250Ω/4∝F
		(G51 ∅ 0,8: 1400m)	inside cabinet)	See chapter 16		Max. 1000m as
					See chapter 16
						stub line
Number of users		… 16	… 16	… 128	1 address	… 32	… 24
connected or					(Max. 25 detec-	LON-Bus de-
		C-Bus devices	I-Bus modules	D-Bus devices			Max. 8 addresses
addresses					tors)	vices
Number of wires		2	26	2	2	2	6
		(+3 wires for emer-
							(+3 wires supply)
		gency operation)
Type of cable		Twisted 1)	Flat cable	Twisted	Twisted	Twisted	Twisted
				(Un-twisted per-	(Un-twisted
				missible)	permissible)
Loop line		✔	–	✔	–	–	–
T-branch		–	–	–	–	✔	–
						(See chapter 18)
Short-circuit proof		Yes		Yes
		Each user con-	–	Each user con-	No	No	Yes
		nected with line		nected with line
		separator		separator
Network structure		Master/master	Master/slave	Master/slave	Master/slave	Master/slave	Master/slave
Scanning		Event-controlled,	Cyclic,	Cyclic		Event-controlled,
				- typ. all 64s	–	presence moni-	Cyclic
		presence monitoring	Event controlled	- Interrupt on		toring	- typ. all 250ms
				alarm		(All 60s)
Principle		Serial Bus		Sensor/actor-Bus	Conventional	Network
			C-Bus	- Cerberus proto-
						- Echelon Chip	Serial bus
		- Cerberus protocol		col 'K31'	- Current gain
			- Cerberus protocol			(LON protocol)	- Cerberus proto-
		- Collision detection		- Serial 8bit	principle
		- Manchester coding	- SPI/Motorola	- Start-up: daisy-	- Voltage levels	- Cerberus	col
				chain		specific telegram

1Calibrated according to cable impedance: 50Ω (MICC) / 110Ω (G51, ø 0.8mm, not shielded)

6.2Modifying the impedance of the various C-Bus cables

C-Bus standard cables have a characteristic impedance of 110Ω. The driver and end-of-line resistors are soldered to solder lugs and can be adapted accordingly with other characteristic impedances (see diagram chapter 6.2.1).

1.Explanation

A cable must be terminated with resistors. The resistance value must correspond to the impedance of the cable. Each C-Bus user has four end-of-line resistors (Ri). In addition two driver resistors (Rd) are integrated on the p.c.b. In order that the resistors can be exchanged easily they are all soldered to solder lugs.

C-Bus p.c.b.	Ri	Rd
B3Q700	R31 ... R34	R49, R50
E3H020	R173, R174, R177, R178	R180, R183

The driver resistors specify the current on the C-Bus. In order that the signal on the

C-Bus always has the same amplitude (1.35Vpp), the following correlation is valid:

Rd = Ri x 3,65 (45Ω < Ri < 200Ω)

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Siemens Building Technologies	007836_a_en_--.doc
Fire & Security Products	03.2004