Defining the Problem:
In a wastewater treatment plant, remotely mounted gas
detectors monitoring Methane CH4 (ceiling), Oxygen O2 (6 ft high) and Hydrogen
Sulfide H2S (floor) have analog outputs. The gas levels need to be saved to
chart recorders located in a control room a long distance away in the plant. To
save on the cost of running copper twisted pair wires, we would like to network
the analog outputs for transmission over the Ethernet infrastructure.
System Requirements:
A ControlLogix PLC in the control room can communicate using
Ethernet/IP protocol. The Ethernet remote I/O will accept 4 – 20mA inputs from
the gas detectors and convert to Ethernet/IP. The PLC will output 4 – 20mA to
the chart recorders nearby. Also, the hazardous area requires Class 1 Div 2
instruments.
Implementing the Solution:
1. In the USB configured XT software, set the IP address,
network parameters and input scaling.
2. Configure the PLC with Acromag’s ControlLogix application
note. This document includes instructions for RSLogix 5000 and RSLinx.
3. With the XT1212-000 software and inputs wired, poll the
module and check the measurements using the test page.
4. Validate the Ethernet/IP communications with an Ethernet
connection between the XT and the PLC.
Why Acromag:
The XT series of Remote I/O has Class 1 Div 2 ratings for
hazardous locations where the Gas Detectors are installed. With simple software
configuration and an application note detailing the PLC configuration,
installation and testing are easily accomplished.
This application note was provided by our supplier Acromag.
For further information about the Acromag products used in this application, please do not hesitate to contact us.
Metromatics I 07 3868 4255 I sales@metromatics.com.au
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