How to establish communication between a gas alarm and the central control system or other DCS systems
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How to establish communication between a gas alarm and the central control system or other DCS systems
Just connect it directly to the DCS card
What the original poster is referring to is the use of alarms to create an independent alarm system, separate from the DCS system. If the alarm system has a communication interface, it can communicate with the DCS
Most manufacturers use the default RS 485 interface, employing the Modbus RTU communication protocol.
As per regulations, gas alarm systems are installed separately, and they are mostly based on PLCs. Connecting the gas detector to the DCS facilitates display and alarm functions, enabling easier management and operation. 1. It can communicate with the DCS via 485 ； 2. A two-way safety barrier can be configured, with one connection to the AI terminal of the PLC in the gas alarm system and the other connection to the AI terminal of the DCS. Choose the method that you find more convenient.
Previously, the gas alarms in our plant were displayed on various alarm controllers on site without any trend display; now they have all been integrated into the DCS system for control.
No, 485 communication is required
That’s the GDS system; the alarm device is connected to the GDS system, and then communication with the DCS is established via Modbus 485
It should be a combustible/toxic gas detection system (GDS), not a separate alarm device; the alarm device is definitely wired directly to the DCS, provided that there is no GDS system
Just as, in the absence of a SIS system, the more critical interlock valves and signals are connected only to the DCS system; however, with a SIS system, they can be connected to the SIS, and then communicate with the DCS via Modbus 485. It is not possible for individual instruments or valves on-site to communicate directly with the DCS