Bacharach ADM800 manual AGM300 Modbus RTU Operation, Protocol Details

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AGM300 MODBUS RTU Operation

Overview

The AGM300 and ADM800 are equipped to communicate with other equipment using the MODBUS RTU protocol. Using this communication channel a MODBUS master device may communicate with up to 15 AGM300s on a communications network, exchanging measurement information, alarm data, fault data, history (logs and trends) and setup information. Additionally, the MODBUS master can control the operating state of an AGM300, placing the AGM300 in any of its different operating modes. The network may be configured such that the AGM300s are connected directly to the MODBUS master device, or the MODBUS master device may communicate with the AGM300s through the ADM800.

(NOTE: This document will assume that the reader is familiar with the various parameters used to set up the AGM300, as well as the different operational modes that the AGM300 may be placed in. If you are unfamiliar with this information, please reference the AGM300 operations manual.)

Protocol Details

A 2 wire RS-485 bus is used for transmission, therefore communication occurs in a Half-Duplex mode. The AGM300 is a slave device and will respond to queries in the MODBUS RTU format from a master device.

Two MODBUS functions are supported. They are function 03 (read holding register) and function 16 (Preset Multiple registers). Please refer to the MODBUS Protocol Reference Guide (available at www.modicon.com/techpubs/techPubNew/PI_MBUS_300.pdf) for protocol detail and use instructions.

Using the two MODBUS functions, a master device may read, modify and write data and status information to any AGM on the network. AGM data is organized into structures (internal to the AGM300) which can be accessed by the MODBUS registers defined in this document. A corresponding set of data structures should be maintained by the master device. These master device data structures become the destination for responses to read queries and sources for preset register commands. When a read holding register query is made by the master device the AGM300 responds by sending the contents of the structure referenced by the specified register. After the master validates the AGM300 response using the CRC bytes, it must then move the data into its matching data structure before individual items may be accessed or modified. Therefore, the master data structure should correspond to the AGM300 data structure byte for byte. Note that some data structures have been divided into multiple registers due to MODBUS RTU message length constrains. To change a setting in the AGM300, the master device first reads the register structure that contains the data item to be modified, makes the desired change, then sends the structure back using the preset multiple register function. If the transaction is successful, the AGM300 sends the appropriate MODBUS response. It is the responsibility of the master device when making modifications to insure that all parameters trasfered fall inside the working limits of the AGM300.

Notes on AGM300 Polling

After the AGM300s are setup and operating, the master device need only poll each AGM for its status register which contains summary data of the AGM’s alarms, faults, and operating state. If exceptions are detected through the status register and more details are required, additional registers can be examined. Also if current PPM values are required, the PPM register provides access to current PPM values for all zones. The AGM300 requires a minimum of 20 seconds to complete a gas concentration measurement for a single zone. Therefore, it is not necessary to poll the AGM300 more frequently than once every 15-20 seconds, as there will not be any new data available/obtained by more frequent polling. In fact, excessive polling will slow the operation of the AGM300. Under no circumstances should the AGM300 be continuously polled at rate faster than 500mS, as this could result in erroneous readings by the AGM300.

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Contents AGM300 / ADM800 Ammonia Gas Monitoring System Rev MayInstruction Table of Contents Introduction How to Use This ManualPlease Read this Manual Carefully Before Use Safety Precautions Hazard Symbols on Monitor Installation CategoryCleaning Altitude LimitFunctional Overview General DescriptionCommunication Options Suggested Location of Sampling PointsChiller Machine RoomStandard Accessories for a 4 Point System LEDLocating the Monitor AGM300 Installation ConsiderationsInspection Installation AGM300 Mounting InstructionsScrew Locations AGM300 Mounting SpecsAGM300 Connecting Air Lines OverviewAGM300 Side View Inlet / Purge PortsConnecting Purge Line Connecting Exhaust LineConnecting Sample Intake Lines Tubing ConsiderationsAGM300 Interior Schematic Do not Apply Power Switches / FusesON/OFF / OUTAGM300 Electrical Wiring VAC InstallationAGM300 AC Input Power and Ground Connections AGM300 Connecting Communication Devices RS-485 ConnectorAmmonia Display Module ADM800 Connection Integrating with Building Management SystemsPersonal Computer Refer to AGM300 PC Software Section Changing Terminator SettingsOUT Multiple AGM’s Connecting to a Building Management SystemRS-485 Connections Between AGM300’s Programming the AGM300 Using PC Software AGM300 PC SoftwareMultiple AGM300’s Connected to a Building Management System Unit Node Terminator Outout Building Management SystemSaving the AGM300 Program to a Disk or Drive To Open a Saved ProgramTo Send a Saved Program to an AGM300 Trend DataUSB Type Laptops Sealevel SYSTEMS, INCCurrent Loop Connector AGM300 Current Loop InterfacesOptional 4-20 mAdc Outputs ConnectionAGM300 Connecting External Alarms AGM300 Relay ConnectorLeak Spill Evacuate Fault Typical AGM300 Relay 1 and Relay 2 WiringADM800 Installation ADM800 Oblique PhotoADM800 Installation Considerations ADM800 Mounting Instructions ADM800 Mounting SpecsADM800 Interior Schematic Front Panel ChassisTo Monitors To HostADM800 Electrical Wiring ADM800 AC Input Power and Ground Connections AGM300 Network ADM800 Communication ConnectionsIntegration with Building Management System Changing Terminator Switch Settings To MonitorADM800 Connecting External Alarms ADM800 Relay ConnectorADM800 Exterior Schematic ADM800 OperationADM800 Overview ADM800 Screen Displays System ScreenPassword Protection Setup ParametersADM800 System Programming Setting the Clock ADM800 Setup ProgrammingClock Setup Screen Navigating to the 1st ADM Setup Screen ContrastNumber of AGM Units AGM Baud RateAudible Alarm PasswordEnabling Building Management System Connection Building Management System Stop BitsNavigating to the 2nd ADM Setup Screen Setting Relay ParametersADM Setup Screen #2 AGM Node AddressAGM300 Setup Programming Navigating to the 1st and then 2nd AGM Setup ScreenScreen #1 AGM Setup Screen #1 AGM Setup Screen #2Number of Zones Installed Alarm Ack ModeLocation Zone Hold TimeRe-Zero Mode Loop 2 FactorAuto Zone ChangeService Timeout Navigating to the 3rd AGM Setup ScreenAGM Setup #3 Screen ADM800 Zone Setup Programming Navigating to the 1st Zone Setup ScreenZone Setup Screen #1 DistanceAverage Temperature Navigating To the 2nd Zone Setup ScreenCurrent PPM Log IntervalSpill Level Re-Setting the Peak PPM ValueEvacuation Level General Operation Functional OverviewWorking with the Zone Screen Zone ScreenZone Screen Hold Mode Zone Screen Alarm ModeFault Conditions System Screen Alarm Mode Working with the System ScreenAGM Setup #1 Screen Alarm Log ScreenSystem Screen Fault Mode Responding To Alarms Working with AlarmsAlarm Summary Screen Alarm Detail Screen Alarm Detail ScreenAcknowledging Alarms Alarm Summary Screen Acknowledge ModeWorking with the Trend Screen Overview Log IntervalNavigating To the Trend Screen Trend ScreenNavigating to the Fault Screen Working with System FaultsFault Screen Reset to Factory Default Settings Critical FaultsViewing Fault Log Clearing System FaultsFault Log Screen Adjusting Calibration Factor Working with the Calibration ScreenNavigating to the Calibration Screen Calibration ScreenCalibration Procedure Working with the Diagnostic Screen Navigating to the Diagnostic ScreenDiagnostic Screen Overview Diagnostic ScreenInstruction Service Mode System Screen Service ModeInstruction Appendix AGM300 / ADM800 Maintenance Servicing Inline FilterServicing Air Lines Replacing FusesIntake Manifolds Optional AccessoriesMA Interface Board ADM800 Logic Diagram RS-485 Communication Protocol Modbus RTU ProtocolAGM300 Modbus RTU Operation Protocol DetailsModbus Mode RTU only Key Comm Protocol ParametersSummary of Registers Data Type AbbreviationsRegister Name Number Type Description TIMREV Unused TIMUnused Minutes RS-485BAUDService mode register to change this parameter Mode. do not Modify use zone hold register orMSB LSBVariable Type Length Description Zone Data Register 0x12xxh R/W 78 bytesGood. do not Modify Instruction Instruction Stpppm To Release the Zone Hold Use the Following Sequence of Steps Fault Log Register Register 0x1900, 0x1901h Bytes Instruction Time record for each of the 100 log points. The format Point to current readingLast 100 log points 2 byes per point Warranty Warranty and ServiceService Products Covered under Warranty and Service Policy Return ProcedureField Repair AGM300 Specifications ADM800 Specifications Instruction Headquarters Hunt Valley Circle, New Kensington, PA

AGM300, ADM800 specifications

The Bacharach ADM 800 and AGM 300 are advanced analyzers designed for efficient monitoring and detection of gases in various applications. Known for their reliability and accuracy, these instruments cater to commercial and industrial sectors, ensuring safety and compliance with environmental regulations.

The Bacharach ADM 800 is a portable gas detection device renowned for its ability to detect multiple refrigerants. With a user-friendly interface, it features a high-resolution display that provides real-time data on refrigerant concentrations, allowing technicians to quickly identify leaks during maintenance operations. One of its standout technologies is a highly sensitive thermal conductivity sensor, which enables the ADM 800 to differentiate between various hydrocarbon refrigerants with precision.

Equipped with data logging capabilities, the ADM 800 can store and retrieve measurement data, making it an invaluable tool for tracking refrigerant trends over time. The device supports USB connectivity for easy transfer of data to computers, facilitating detailed reporting and analysis. Its robust design incorporates a protective casing that ensures durability in challenging work environments, making it ideal for both field use and stationary applications.

On the other hand, the Bacharach AGM 300 is specifically crafted for continuous gas monitoring in HVAC systems. This stationary device excels in measuring concentrations of gases such as CO, CO2, and various refrigerants, ensuring optimal performance and compliance. The AGM 300 uses advanced electrochemical sensors for precise gas measurements, providing real-time feedback and alerting users to any hazardous conditions.

One of the notable features of the AGM 300 is its ability to integrate seamlessly with building management systems, enabling centralized control and monitoring of gas levels across multiple locations. This connectivity enhances the safety of industrial and commercial spaces by allowing for automated responses to detected gas levels, which can significantly mitigate risks associated with gas leaks.

Both models emphasize user-centric design, with intuitive interfaces and clear displays, making them accessible even to those with minimal training. Additionally, their low maintenance requirements and long sensor life contribute to reduced operational costs.

In conclusion, the Bacharach ADM 800 and AGM 300 are exemplary solutions for gas detection and monitoring. Their advanced technologies, robust features, and user-friendly designs make them indispensable for ensuring safety and regulatory compliance in various environments.
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