Notes on Network Topologies

AGM300s may be connected directly to the MODBUS network or they may be connected to the network through an ADM800. In either case, each AGM300 must have a unique node ID. Up to 15 AGM300s can be connected directly to the MODBUS network.

If AGM300s are accessed via an ADM800 connected to a MODBUS network, the ADM800 “BMS enabled” parameter must be set equal to “1” via the “ADM SETUP” screen on the ADM800. The same commands and registers are used to communicate with the AGM300 directly or through the ADM800. If the communications is through the ADM800, it monitors each MODBUS message to determine if the message is intended for one of the AGM300s it is connected to. If it is, the ADM800 passes the message through to the AGM300s. If it is not, the message is not passed through. The ADM800 does not make any modifications to MODBUS messages. It simply passes the query through to the AGM300, and passes the response back to the MODBUS master. In other words, it allows the AGM300s to be logically connected to the MODBUS network, when physically they are connected to the local ADM800 network. It is very important to understand that the ADM800 will only pass messages through to the AGM300 when the ADM800 is either in the “SYSTEM” screen or the “ZONE VIEW” screen. If the ADM800 is in any other screen, it will return a MODBUS “busy” exception response (exception code 06).

All ADM800 screens except the SYSTEM and ZONE VIEW screens have a 10 minute timeout interval, after which the screen will return to either the SYSTEM or ZONE VIEW screen, depending on which one it was last in. Also, the ADM800 can be password protected such that a password entry is required in order to view screens other than the SYSTEM or ZONE VIEW screen.

Key Comm Protocol Parameters

MODBUS Mode: RTU only

AGM300 Baud Rate: Default is 19,200. Programmable as defined in System data register

Parity: No Parity

Stop Bits: Default is 1. Can be set for 2 via System data register

Maximum Response Time: 4000mS when directly accessing the AGM300. 8,000mS when accessing the AGM300 through the ADM800.

Error Checking: CRC per MODBUS specifications

Also of note is the fact that all data sent out from the AGM-300 is in “little endian” byte order (Least significant byte followed by most significant byte). This should be taken into account if the master that process the data is a “big endian” type. Non-data information (starting address, number of points, etc.) follows normal MODBUS protocol, which is Big Endian.

Instruction 3015-4275

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Bacharach AGM300, ADM800 manual Key Comm Protocol Parameters, Modbus Mode RTU only
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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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