INSTRUCTION MANUAL PLUG AND SEND WIRELESS MONITOR SYSTEM TABLE OF CONTENTS

Transcription

1 DEVAR Inc. 706 Bostwick Ave., Bridgeport CT Tel Fax INSTRUCTION MANUAL PLUG AND SEND WIRELESS MONITOR SYSTEM TABLE OF CONTENTS 1.0 General Description Theory Of Operation Calibration Specifications... 6 Fig. 1 Link Protocol... 4 Fig. 2 Field Wiring, Input... 5 Fig. 3 Field Wiring, Output... 5 Fig. 4 Adding external relays... 7 Fig. 5 Typical antenna configuration... 8 Instruction Manual 3019 Indicator/Controller Page 1 of H

2 INSTRUCTION MANUAL PLUG AND SEND WIRELESS MONITOR SYSTEM 1.0 General Description The Devar Plug and Send Wireless Monitoring System is designed to transmit analog or discrete ( on/off ) information over a non-licensed portion of the VHF radio spectrum. The system accomplishes this by broadcasting very short pulses of radio energy with the transmitted information encoded in the length of time between pulses. The system consists of a transmitter unit and a receiver unit. The transmitter unit is powered by an internal 12 volt battery with AC powered circuitry to keep the battery charged. It accepts one 4 to 20 ma input and three discrete ( dry contact ) inputs. The Devar model 3019, a 4 digit LED, AC powered indicator, is used to display the 4 to 20 ma process input signal in engineering units. A green LED, at the front of the unit, turns on and off as the transmitter transfers data to the receiver. The length of time that the LED is turned on is a function of the analog input. The length of time that the LED is turned off is a function of the discrete inputs which have been activated. The receiver which is an AC powered unit, demodulates the signal coming from the transmitter and produces a 4 to 20 ma output which is equal to the 4 to 20 ma input at the transmitter. A four digit LED indicator, the Devar model 3019, is provided to display the 4 to 20 ma output in engineering units. The receiver also provides three discrete outputs which correspond to the discrete inputs at the transmitting unit. The discrete outputs are in the form of three open drain MOS-FET transistors which are referenced to the system common. Three red LED s mounted on the front of the unit, are also connected to the discrete output transistors. The red LED s will turn on when a discrete input is detected. A green LED, also at the front of the unit, turns on and off as data is being received from the transmitter. Unlike the green Led at the transmitter unit, this Led flashes once at the start of the cycle and flashes twice at the end of the cycle. If no data is received from the transmitter, or if the input falls below 3 ma, for a period of 4.5 minutes, the green LED will stay on continuously indicating a loss of communication. A normally open switch, also in the form of an open drain MOS-FET transistor, closes as a loss of signal alarm. Should the receiver fail to receive data from the transmitter, the last valid reading displayed and corresponding milliamp output will be retained until new valid data is received. Page 2 of 8

3 2.0 Theory of Operation Data is transmitted as a series of time modulated pulses. At the start of the cycle the transmitter will transmit a 10 watt, MHz, digitally encoded pulse. This pulse marks the start of the transmission cycle and contains the identity of the transmitting unit. The transmitter will then transmit a second pulse marking the end of the cycle. The value of the 4 to 20 ma input signal is encoded in the time duration between the start pulse and the stop pulse. The status of the discrete inputs is encoded in the time duration between the last stop pulse and the next start pulse, see figure 1. The receiving unit detects the radio pulses from the transmitter and demodulates them to produce the 4 to 20 ma and discrete switch outputs. Each transmitter has its own identification code. The receiver will only respond to the transmitter with a matching identification code. The identification code is set at the factory to one of 65,536 possible values. 3.0 Calibration The 4 to 20 ma input applied to the transmitter is displayed in engineering units by the The display can be recalibrated at any time from the front key pad, by following the instructions in the 3019 Instruction manual. The RCU board in the receiver decodes the transmitted data and produces a 4 to 20 ma signal. This signal is applied to the input of the 3019 Controller mounted in the door of the receiver. The display of the 3019 can be reconfigured at any time by means of the front keypad, see the 3019 instruction manual. The 3019 then produces a 4 to 20 ma output, which can be scaled from the key pad, by the user. The 4 to 20 ma output from the 3019 is scaled with respect to the engineering units being displayed on the LED display. Therefore, if the 3019 display is rescaled the 4 to 20 ma output will also have to be rescaled. Page 3 of 8

4 START PULSE STOP PULSE START PULSE STOP PULS Analog Data Discrete Data Analog Data 3 to 21 ma 1 to 51 sec 0, 1, 2 or 3 Discretes 52 to 80 sec LED ON LED ON LED OFF DISCRETE DATA ( contact closure ) PERIO D( sec. ) = SWITCH CLOSED ANALOG DATA ( 4 to 20 Ma ) PERIOD ( SEC. ) FIG. 1: Link Protocol Page 4 of 8

5 TRANSMITTER N.C. TO RADIO N.O. EXT LED RIU 4/20 ma IN N.O. DISC 1 N.O. DISC 2 N.O. DISC 3 CHARGER /20 ma INPUT + 12 VDC + 24 VDC GND AC 120 VAC 60 Hz ACC FIG. 2: Field wiring, input DISCRETE INPUTS RECEIVER LOSS OF SIGNAL ALARM /20 ma OUT N.O. EXT LED N.O. DISC 3 N.O. DISC 2 N.O. DISC 1 N,O. ALARM DISCRETE OUTPUTS RCU CHARGER N.C. FROM RADIO 1 + 4/20 ma OUTPUT GND AC 120 VAC 60 Hz 0.11 A ACC FIG. 3: Field wiring, output Page 5 of 8

6 4.0 Specifications 4.1 Transmitter Unit a. Analog input... 3 to 21 ma b. Input voltage drop to 4.98 volts c. Discrete inputs... up to 3 dry contacts 500 :A sink current d. Power requirement VAC, 50/60 Hz, 13 VA e. Internal battery volts, 4 amp. hours f. Current draw from battery... 2amp, momentary on transmit 100 ma, average continuous 4.2 Receiver Unit a. Analog output... 4 to 20 ma, into 1200 ohms b. Discrete outputs... 3 solid state switches open drain MOS-FET, 300mA c. Loss of signal alarm... solid state switch open drain MOS-FET, 300 ma d. Power requirement VAC, 50/60 Hz, 13 VA 4.3 System a. Resolution... 8 bits b. Accuracy % of span, with occasional excursions to 1% 4.4 Radio a. Frequency MHz b. Power watt 4.5 Mechanical a. Enclosure x 7.5 x 7 polycarbonate, NEMA 4X b. Access... three ½ water tight cord connectors grip range 0.250" to 0.375" Dia. c. RF connector... UHF Page 6 of 8

7 W/ORN W/BLU W/GRN W/YEL RED LED RED LED RED LED GRN LED W/RED VIEW FROM INSIDE OF DOOR 4/20 ma OUT RCU N.C. TO RADIO N.O. DISC 1 N.O. DISC 2 N.O. DISC 3 N.O. EXT LED + 12 V External relays can be added to the discrete output terminals of the Plug and Send Receiver Unit as shown above. Select a 12 volt relay with a coil resistance of 185 ohms or more. A diode must be connected across the relay coil to prevent damage to the discrete output circuitry. Any general purpose signal diode with a breakdown voltage of 75 volts or greater can be used. FIG. 4: Adding external relays Page 7 of 8

8 UP TO 5 MILES 17 FT WHIP 9 FT MIN 17 FT WHIP 40 FT RECEIVER GND TO BLDG. 10 FT MAST MINIMUM EARTH GND REMOTE TRANSMITTER FIG. 5: Typical antenna configuration Page 8 of 8