Telemetry is used in combination with both relay based and PLC based control systems, allowing the control system to communicate with a remote operator, a remote operator to communicate with a control system, or both.
For applications where it is only required that the system communicate with a remote operator, autodialers are the best option. An autodialer takes discrete input signals, whether from a relay or PLC, and alerts the operator(s) by dialing pre-programmed telephone number(s) and playing a pre-determined message. As an example, if a soil vapor extraction system shut down because there was a high level alarm in the vapor/liquid separator, the operator(s) could be automatically notified of this condition by having that alarm as an input to the autodialer. Autodialers are capable of receiving up to 8 input signals and communicating with 32 different telephone numbers. The more sophisticated models can also record alarm history and log data from analog inputs.
In order for a remote operator to communicate with and control treatment equipment, it is necessary to install a modem in the control system. This type of communication is only possible with a PLC based control system, or a relay based control system with a special add-on. The modem can be compatible with either land-line or cellular signals. Various levels of communication and control are available:
- For users simply requiring status updates, a remote server can contact the control system every 24 hours to retrieve run status, alarm history, flow totals, etc. This data is then transmitted to the operator(s) via an email.
- To remotely control treatment equipment, communication and interface software is available. The software is installed directly on the operator’s computer, allowing them to view system status in real time, control system operation including individual components, alter setpoints for transmitters and alarms, view alarm history, and view data logs.
- For remote control without installing software, it is possible to handle the communication through a server. By communicating through a server, rather than software stored on an individual computer, the system operation can be controlled from any computer through a web browser.
When choosing a telemetry option, it is important to consider the level of remote communication and control required and the available communication signal types.
MLE Equipment uses autodialers manufactured by Paravox and Sensaphone. For the more sophisticated telemetry options, MLE Equipment designs and builds the communication hardware into control systems using our in-house designed Site Link software. These systems are built in a UL-approved facility and can be built with UL, CSA, MET, or ESA approval. Please see the provided specification sheets and manuals for more detailed information on telemetry.
