Varec 4000 manual Encoder Battery Backup, Temperature Measurement, Host Communication

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4000

Theory of Operation

 

 

7.7Encoder Battery Backup

The ATT includes battery backup for the encoder. This allows level to be maintained across a power failure. Several consideration are made to protect the battery from being fully discharged.

1.The battery must be physically enabled by the microprocessor. This allows the battery to be shipped connected without being discharged.

2.Service personnel can turn the battery off. This will allow the battery to be disabled when a tank or a transmitter is to be taken out of service for an extended period of time.

3.On-board circuitry limits the battery backup time to 24 hours. This allows battery life to be extended even if serv- ice personnel forget to disable the battery during extended power outage conditions.

The battery is automatically turned on when the ATT is calibrated with a given level.

7.8Temperature Measurement

The ATT measures temperature directly using a high accuracy 16 bit analog to digital converter. Temperature inputs can be either a 3-wire Copper or Platinum RTD. Optionally the temperature can be manually entered. The 4120 Multi- Element Temperature transmitter can be used as a replacement to a spot temperature bulb (RTD).

7.9Host Communication

The Modbus host interface permits the ATT to directly communicate with any distributed control system utilizing the Gould Modbus protocol. The Modbus protocol defines two data formats, ASCII and RTU. The RTU format specifies that all data is in binary. The ASCII format specifies that all data is in ASCII (producing messages twice as long as RTU format messages). The ATT only supports the RTU message format.

The Modbus protocol permits a host computer to view field devices as having analog input registers, analog output registers, digital input registers, and digital output registers. Measured parameters, configuration parameters, and status conditions are mapped to Modbus analog and digital registers.

A non-standard Modbus floating point register extension has been defined for use by the ATT. This format extension permits floating point data to be directly read from and written to any Modbus device. The IEEE 754 standard floating point format is used. Each floating point register consists of four bytes.

To provide compatibility with future enhancements, data written to undefined registers are accepted and ignored. Data read from undefined registers returns a value of zero (0).

The supported Modbus functions and exceptions are indicated in the following tables.

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Contents Installation Operations Manual Page Copyright Disclaimer of Warranties Safety Precaution Definitions Safety Precautions Tank Gauge Transmitter Introduction Tank Gauge Transmitter Glossary Tank Gauge Transmitter Viii Introduction Using This ManualOperation ConfigurationConstruction Installation Part Number Gauge Adapter Kit Mounting the EquipmentATT Wiring WiringWiring Preparation Connecting Input PowerTerminal Block One TB1 Terminal Block Two TB2 Connecting Host CommunicationTypical EIA485 Wiring ATT EIA485 WiringTypical EIA485 System Wiring Typical Mark/Space Field Wiring ATT Mark/Space WiringConnecting the Handheld Terminal Connecting the RTDWiring Completion Installation CheckoutConfiguration Parameters Configuration1200 Hand Held Terminal Function Key DescriptionTerminal Mode Configuration 1200 Hand Held Terminal Terminal Mode OperationMenu Operation Main Menu Description Main MenuSummary Menu Description Summary MenuConfiguration Menu Description Configuration MenuHost Menu Description Host MenuQuick Setup General Configuration Imperial Fractional 1900 Quick Setup DefaultsHost Configuration Imperial Decimal 1900 Quick Setup Defaults 3 0-20 Meter 1900 Quick Setup Defaults 4 0-30 Meter 1900 Quick Setup Defaults Imperial Decimal 1800 Series Transmitter Quick Setup Imperial Fractional 1800 Series Transmitter Quick Setup7 0-20 Meters 1800 Series Transmitter Quick Setup 8 0-30 Meters 1800 Series Transmitter Quick SetupImperial Modbus Quick Setup Defaults Metric Modbus Quick Setup Defaults Maintenance Maintenance and TroubleshootingBattery Replacement ATT Error Status Conditions TroubleshootingError Message Description ATT Status Conditions ATT Configuration Error CheckingStatus Condition Description Host Communication Loopback Tests Model 1200 Error MessagesSpecifications and Physical Characteristics SpecificationsInput Power EnvironmentalLevel Measurement Intrinsic Safety Safety Agency ApprovalsExplosion Proof Agency Acronym RequirementMajor System Assemblies and Components Assembly/Component Part NumberCommunications Order Codes Order Codes CPU Board Theory of OperationStatus Inputs and Outputs Back-up BatteryAtti Communications Port Host Communications InterfacesTemperature Measurement Encoder Battery BackupHost Communication Function Number Mark/Space Host InterfaceNumber Exception Compatibility with Varec Tank Polling Unit Modbus Support over Mark/Space Host InterfaceTheory of Operation Model 4040 Display Unit ATT Family of ProductsModel 4050 Digital Input/Output Unit Relay SpecificationsDigital Outputs Digital InputsIntroduction Modbus ImplementationImplementation Modbus Implementation Integer Registers Functions and Data FormatsTerm Definition Host Request Integer DataATT Response Character Data Packed Bit Data Coded DataFloating-Point Data Floating-Point RegistersTwo 16-bit Registers Format Floating Point DataOne 32-bit Register Format Status Bit Data Status BitsException Responses Exception Response ReasonLoopback Test Data Out of RangeHardware Implementation Register Number Type Description Integer Register MapRegister Number Sw Ver0-1 Noise Reject Type Status Bit Register Map Floating Point Register MapModbus Implementation 10.1 4000TIFMO Optional Interfaces10.2 4000GEFMO 10.3 4000LJFMO10.6 4000GMFMO 10.5 4000WBFMOAdv Hi Level GlossaryDband TSU Tank Gauge Transmitter 4000 Your official representative Your offical representative
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