Omega Vehicle Security CN3271 Series manual Inductive Loads, Serial Interface

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C.2) Inductive Loads

High voltage transients may occur switching inductive loads.

Through the internal contacts these transients may introduce disturbances which can affect the performance of the instrument.

For all the outputs, the internal protection (varistor) assures a correct protection up to 0.5 A of inductive component.

The same problem may occurs when a switch is used in series with the internal contacts as shown in Fig. 9.

D) Serial Interface

For units built with optional RS-485 communication interface.

RS-485 interface allows to connect up to 30 devices with one remote master unit.

	I			A/A'	A'/A
	N
	N	11				M
	S	11				M
	S					A
	T				B'/B	A
	T			B/B'		S
	R
	R	12
	U					T
						T
						E
						E

C

R

LOAD

POWER

LINE

M	COMMON	R
E	COMMON	R
N	13
N
T

Fig. 10 - RS-485 WIRING

Fig. 9 EXTERNAL SWITCH IN SERIES WITH THE INTERNAL CONTACT

In this case it is recommended to install an additional RC network across the external contact as show in Fig. 9

The value of capacitor (C) and resistor (R) are shown in the following table.

LOAD	C	R	P.	OPERATING
(mA)	(∝F)	( Ω )	( W )	VOLTAGE

<40 mA	0.047	100	1/2	260 V AC
<150 mA	0.1	22	2	260 V AC
<0.5 A	0.33	47	2	260 V AC

The cable involved in relay output wiring must be as far away as possible from input or communica- tion cables.

The cable length must not exceed 1.5 km at 9600 BAUD.

NOTES:

1)This RS 485 serial interface is insulated.

2)The following report describes the signal sense of the voltage appearing across the interconnection cable as defined by EIA for RS-485.

a)The ” A ” terminal of the generator shall be negative with respect to the ” B ” terminal for a binary 1 (MARK or OFF) state.

b)The ” A ” terminal of the generator shall be positive with respect to the ” B ” terminal for a binary 0 (SPACE or ON).

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19/04/2004, 15.07

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Contents CN3271-add2.pmd 19/08/2004 OMEGAnet On-LineService Internet e-mail Info@omega.com Contents Mounting Requirements Screw Bracket PanelWithout RS-485 With RS-485 Dimensions and Rear Terminal BlocksPanel Cutout Wiring Guidelines RTD Input Linear Input MA, mV and V Inputs WiringRelay Outputs Logic Input for models with RS-485 onlyOUT 1 Class Use cupper conductors onlySerial Interface Inductive LoadsAA/A Power Line and grounding100 to 240 Vac 500 mA 250 100/240 V AC 125 mAHigh Low Limiter without RS-485 High Low Limiter with RS-485Configuration KEY Functions Configuration ProcedureSerial Interface Protocol R7 = Alarm action on input fault R5 = Offset AdjustmentType Value R2 = Decimal Point PositionHi.Lo = High and low limit for special process C2 = Rearming ModeConstant Alarm Function = Rearm at Power-up Auto = Automatic rearm= Alarm configuration = Shutdown memoryP3 = Alarm Action Example for P2 = H.A.A.cExample for P2 = H.L Alarm Standby mask Function = Safety LockT1 = Timeout Selection Normal Display Mode Operating ModeFlashes when alarm is on IndicatorsNormal Display Mode to Operative Parameter Display Mode Operative Parameter Display ModeOperating Parameters Example 1 C1 = Hi and C2 = O Example 2 C1 = Hi and C2 = Limiter functionAlarm functions Serial LInk optionalDevice can be connected to a host computer via serial link Error Messages Error MessagesError List Dealing with Error MessagesPower consumption 8 VA General SpecificationsCommon mode rejection ratio Temperature Drift CJ excludedLinear Inputs Inputs ThermocoupleLogic Inputs AlarmOutputs OutputSerial Communication Interface Option MaintenanceDefault Operating Parameters List Default ParametersLHL-A-NEUTRO.pmd 19/04/2004 Second Seconds Appendix A.3 Appendix B Thermocouple Compensating Cable Color Codes Return Requests / Inquiries Data Acquisition